uart.c doesn't compile on PlatformIO for ESP32-C6

[hesara]

For PlatformIO and ESP32-C6, at least for the Seeed XIAO ESP32-C6 with the Arduino framework, it seems that an additional include in hal/uart.c is needed for it to compile:

#include "soc/lp_clkrst_struct.h"

See also #162 and the related PR #158 .
Adding the include fixes the compilation, but I haven't tested this with real DMX hardware yet.

Using this PlatformIO environment:

platform = https://github.com/mnowak32/platform-espressif32.git#boards/seeed_xiao_esp32c6
platform_packages = 
    framework-arduinoespressif32 @ https://github.com/espressif/arduino-esp32.git#3.0.2
    framework-arduinoespressif32-libs @ https://github.com/espressif/arduino-esp32/releases/download/3.0.2/esp32-arduino-libs-3.0.2.zip
board = seeed_xiao_esp32c6
framework = arduino
lib_deps =
    someweisguy/esp_dmx @ ^4.1.0