esp32/boards: Use auto xtal freq config instead of default 40MHz.

Auto-detection of the crystal frequency is convenient and allows for a
single binary for many different boards.  But it can be unreliable in
certain situations so in production, for a given board, it's recommended to
configure the correct fixed frequency.

ports/esp32/boards/sdkconfig

@@ -13,6 +13,7 @@ CONFIG_LOG_BOOTLOADER_LEVEL_WARN=y
 # ESP32-specific
 CONFIG_ESP32_DEFAULT_CPU_FREQ_240=y
 CONFIG_TASK_WDT_CHECK_IDLE_TASK_CPU0=n
+CONFIG_ESP32_XTAL_FREQ_AUTO=y
 
 # FreeRTOS
 CONFIG_FREERTOS_UNICORE=y

ports/esp32/boards/sdkconfig.spiram

@@ -14,6 +14,7 @@ CONFIG_LOG_BOOTLOADER_LEVEL_WARN=y
 CONFIG_ESP32_DEFAULT_CPU_FREQ_240=y
 CONFIG_SPIRAM_SUPPORT=y
 CONFIG_TASK_WDT_CHECK_IDLE_TASK_CPU0=n
+CONFIG_ESP32_XTAL_FREQ_AUTO=y
 
 # FreeRTOS
 CONFIG_FREERTOS_UNICORE=y