drivers: bluetooth: hci: Increase default RX stack size

The `BT_DRV_RX_STACK_SIZE` config is used by HCI drivers to determine a
suitable stack size for their RX thread. These threads handle the HCI
transport and pass HCI messages to the Bluetooth host via `bt_hci_recv()`.
Previously, the default stack size was 256 bytes, but it seems to be too
small currently.

Measuring the peak stack usage of `bt_hci_recv()` in different scenarios
indicates that the function needs over 300 bytes of stack. Thus, an RX
thread stack size of 512 should cover that and leave some margin.

(cherry picked from commit fa9126f)

Original-Signed-off-by: Kalle Kietäväinen <[email protected]>
GitOrigin-RevId: fa9126f
Cr-Build-Id: 8724909411128659441
Cr-Build-Url: https://cr-buildbucket.appspot.com/build/8724909411128659441
Copybot-Job-Name: zephyr-main-copybot-downstream
Change-Id: Ib8b717485f4ad87c630aead18b4523cb002a68dc
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/+/6196366
Tested-by: ChromeOS Prod (Robot) <[email protected]>
Bot-Commit: ChromeOS Prod (Robot) <[email protected]>
Commit-Queue: ChromeOS Prod (Robot) <[email protected]>

Author: Kalle Kietäväinen

drivers/bluetooth/hci/Kconfig

@@ -295,7 +295,7 @@ config BT_DRV_RX_STACK_SIZE
 	default BT_RX_STACK_SIZE if (BT_H4 || BT_HCI_RAW_H4)
 	default BT_STM32_IPM_RX_STACK_SIZE if BT_STM32_IPM
 	default HCI_NXP_RX_STACK_SIZE if HCI_NXP_RX_THREAD
-	default 256
+	default 512
 	help
 	  Stack size for the HCI driver's RX thread.