drivers/uart/Kconfig: Select 8250 mem when 8250 mem32 is enabled

Users of DRIVERS_UART_8250MEM_32 would have to also select
DRIVERS_UART_8250MEM to avoid missing Kconfig dependencies. Instead,
do what the OXPCIE driver dies and select the appropriate options.

Change-Id: I40d93df024fcb3a9ad6dc51d6a5966e7b1b6c07f
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/11786
Tested-by: build bot (Jenkins)
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

src/drivers/uart/Kconfig

@@ -20,7 +20,7 @@ config DRIVERS_UART_8250MEM
 config DRIVERS_UART_8250MEM_32
 	bool
 	default n
-	depends on DRIVERS_UART_8250MEM
+	select DRIVERS_UART_8250MEM
 
 config HAVE_UART_SPECIAL
 	bool

src/soc/intel/skylake/Kconfig

@@ -141,7 +141,6 @@ config UART_DEBUG
 	default n
 	select CONSOLE_SERIAL
 	select DRIVERS_UART
-	select DRIVERS_UART_8250MEM
 	select DRIVERS_UART_8250MEM_32
 
 config CHIPSET_BOOTBLOCK_INCLUDE