xtensa/esp32s3: Fix CONSOLE_DEV clobbered by USBSERIAL macro.

[FelipeMdeO]

Summary

• Why change is necessary (fix, update, new feature)? Fix — a boot-time
  hang/reset-loop bug.
• What functional part of the code is being changed?
  arch/xtensa/src/esp32s3/esp32s3_serial.c, the CONSOLE_DEV macro
  selection logic used by the ESP32-S3 serial driver.
• How does the change exactly work (what will change and how)?
  When CONFIG_ESP32S3_USBSERIAL is enabled at the same time as a real
  UART is selected as the system console (CONFIG_UARTx_SERIAL_CONSOLE),
  an unconditional #define CONSOLE_DEV g_uart_usbserial silently
  overrides the correct earlier definition that pointed CONSOLE_DEV at
  the chosen UART device. xtensa_earlyserialinit() then calls
  esp32s3_setup(&CONSOLE_DEV) — a function only valid for a
  struct esp32s3_uart_s — on what is actually g_uart_usbserial, whose
  priv points to an unrelated struct esp32s3_usbserial_s. Reading
  priv->id off the wrong struct returns garbage, which is then used to
  compute a UART register address; the resulting access to invalid IO
  hangs the CPU until the RTC watchdog resets the board, in a loop,
  before NSH ever starts. The fix guards the USBSERIAL assignment with
  !defined(CONSOLE_DEV), mirroring the pattern already used a few lines
  below in the same file for TTYS1_DEV/TTYS2_DEV.
• Related NuttX Issue: none filed yet.

Impact

• Is new feature added?
  Is existing feature changed? NO — pure bug fix,
  no behavior change for any config that was working correctly before
  (the only configs affected are ones where CONSOLE_DEV was silently
  wrong, i.e. already broken).

Testing

I confirm that changes are verified on local setup and works as intended:

• Build Host(s): Linux (x86_64), GCC via the xtensa-esp32s3-elf
  toolchain (esp-elf 14.2.0).
• Target(s): xtensa, Seeed XIAO ESP32-S3 (esp32s3-xiao), custom
  out-of-tree defconfig with CONFIG_ESP32S3_UART0=y,
  CONFIG_UART0_SERIAL_CONSOLE=y, CONFIG_ESP32S3_USBSERIAL=y.
• Reproduction: flash a config with a UART selected as
  SERIAL_CONSOLE while CONFIG_ESP32S3_USBSERIAL is also enabled, and
  watch the UART console — it boot-loops instead of reaching NSH.

Testing logs before change:

ESP-ROM:esp32s3-20210327
Build:Mar 27 2021
rst:0x10 (RTCWDT_RTC_RST),boot:0x9 (SPI_FAST_FLASH_BOOT)
...
*** Booting NuttX ***
dram: lma 0x00000020 vma 0x3fc8e7e0 len 0x184c   (6220)
iram: lma 0x00001874 vma 0x40374000 len 0x8494   (33940)
...
total segments stored 7
<hang here -- nothing else is ever printed>

<~8s later, resets and repeats identically, forever>

Testing logs after change:

nsh> uname -a
NuttX 13.0.1-RC0 734c06c4f3-dirty Sep  3 2026 11:50:28 xtensa esp32s3-xiao
nsh> ls /dev
/dev:
 console
 i2c0
 mmcsd0
 null
 ttyACM0
 ttyS0
 uorb/
 usensor
 zero
nsh>

[FelipeMdeO]

@acassis , can you review this PR too, please?