drivers: serial: uart_max32: Add async mode support

This commit adds asynchronous mode support to MAX32 UART driver. Each
direction uses a single DMA channel that is assigned in devicetree
configuration.

Asynchronous mode also depends on interrupts to refresh receive
timeouts.

Signed-off-by: Tahsin Mutlugun <Tahsin.Mutlugun@analog.com>

Author: ttmut

drivers/serial/Kconfig.max32

@@ -10,6 +10,8 @@ config UART_MAX32
 	select SERIAL_HAS_DRIVER
 	select SERIAL_SUPPORT_INTERRUPT
 	select PINCTRL
+	select SERIAL_SUPPORT_ASYNC if DT_HAS_ADI_MAX32_DMA_ENABLED
+	select DMA if UART_ASYNC_API
 	help
 	  This option enables the UART driver for MAX32 family of
 	  processors.