boards/arm/rp23xx: add Raspberry Pi Pico 2 W board (CYW43439 Wi-Fi)

Add a board port for the Raspberry Pi Pico 2 W (RP2350 + Infineon
CYW43439).  The board reuses the existing raspberrypi-pico-2 port and
adds support for the onboard CYW43439 Wi-Fi device, driven through a new
RP2350 PIO-based gSPI transport (arch/arm/src/rp23xx/rp23xx_cyw43439.c)
that plugs into NuttX's existing bcm43xxx (bcmf) FullMAC driver.

A telnet defconfig is provided that associates to an AP (NETINIT WAPI),
obtains a DHCP lease, and exposes an NSH shell over TCP/telnet.

This board port and the RP2350 PIO-gSPI CYW43439 driver were developed
with Claude Code (Anthropic's agentic coding tool) and validated on real
Pico 2 W hardware: Wi-Fi association, DHCP, and a TCP/telnet session over
the CYW43439.

Signed-off-by: Ricard Rosson <ricard@groundbits.com>
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: ricardgb

arch/arm/src/rp23xx/CMakeLists.txt

@@ -89,4 +89,8 @@ if(CONFIG_CRYPTO_CRYPTODEV_HARDWARE)
   list(APPEND SRCS rp23xx_crypto.c)
 endif()
 
+if(CONFIG_IEEE80211_INFINEON_CYW43439)
+  list(APPEND SRCS rp23xx_cyw43439.c)
+endif()
+
 target_sources(arch PRIVATE ${SRCS})

arch/arm/src/rp23xx/Make.defs

@@ -92,3 +92,7 @@ endif
 ifeq ($(CONFIG_CRYPTO_CRYPTODEV_HARDWARE),y)
 CHIP_CSRCS += rp23xx_crypto.c
 endif
+
+ifeq ($(CONFIG_IEEE80211_INFINEON_CYW43439),y)
+CHIP_CSRCS += rp23xx_cyw43439.c
+endif