feat: use baudrate from EspSerial in EspNuttx (RDT-1275)

[fdcavalcanti]

Description

This PR modifies the NuttxSerial class.

It had a fixed flash baud rate (for Espressif devices) and now it can be changed through the command line. It simply removes the custom entry for baud rate and uses the baud from the inherited EspSerial class.

Related

Testing

Tested by running Pytest without setting --esptool-baud and than by setting to a customized value.
The flash is first erased and then the firmware is uploaded. Baud rate line is marked.

• Without setting esptool-baud:

==========================================
INFO:root:Flashing device
========================================================================================= test session starts =========================================================================================
platform linux -- Python 3.12.3, pytest-8.3.4, pluggy-1.5.0
rootdir: /dev
configfile: null
plugins: html-4.1.1, embedded-1.16.0, metadata-3.1.1
collected 77 items / 76 deselected / 1 selected                                                                                                                                                       
[...]
2025-04-16 14:18:13 Stub running...
2025-04-16 14:18:13 Changing baud rate to 921600  <<<<<=================
2025-04-16 14:18:13 Changed.
2025-04-16 14:18:13 Configuring flash size...
2025-04-16 14:18:13 Flash will be erased from 0x00000000 to 0x0003efff...
2025-04-16 14:18:13 Compressed 255036 bytes to 113121...
Wrote 255036 bytes (113121 compressed) at 0x00000000 in 1.8 seconds (effective 1126.0 kbit/s)...
2025-04-16 14:18:15 Hash of data verified.
2025-04-16 14:18:15 
2025-04-16 14:18:15 Leaving...
2025-04-16 14:18:15 Hard resetting via RTS pin...
[...]
============================================================================ 1 passed, 76 deselected, 3 warnings in 6.08s =============================================================================

• Setting --esptool-baud=460800:

==========================================
INFO:root:Flashing device
========================================================================================= test session starts =========================================================================================
platform linux -- Python 3.12.3, pytest-8.3.4, pluggy-1.5.0
rootdir: /dev
configfile: null
plugins: html-4.1.1, embedded-1.16.0, metadata-3.1.1
collected 77 items / 76 deselected / 1 selected                                                                                                                                                       
[...]
2025-04-16 14:28:26 Stub running...
2025-04-16 14:28:26 Changing baud rate to 460800
2025-04-16 14:28:26 Changed.
2025-04-16 14:28:26 Configuring flash size...
2025-04-16 14:28:26 Flash will be erased from 0x00000000 to 0x0003efff...
2025-04-16 14:28:26 Compressed 255036 bytes to 113121...
Wrote 255036 bytes (113121 compressed) at 0x00000000 in 2.6 seconds (effective 772.6 kbit/s)...
2025-04-16 14:28:29 Hash of data verified.
2025-04-16 14:28:29 
2025-04-16 14:28:29 Leaving...
2025-04-16 14:28:29 Hard resetting via RTS pin...
[...]
============================================================================ 1 passed, 76 deselected, 3 warnings in 6.98s =============================================================================

---

Checklist

Before submitting a Pull Request, please ensure the following:

• 🚨 This PR does not introduce breaking changes.
• All CI checks (GH Actions) pass.
• Documentation is updated as needed.
• Tests are updated or added as necessary.
• Code is well-commented, especially in complex areas.
• Git history is clean — commits are squashed to the minimum necessary.

[hfudev]

LGTM!