pl01x: Convert CONFIG_PL01X_SERIAL to Kconfig

We want to use Kconfig logic to depend on whether pl01x devices
are built in, so let's convert their inclusion selection to Kconfig.

This round goes to pl01x.

Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 99aa817..4167683 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -459,6 +459,12 @@
 	help
 	  Select this to enable a UART for platforms using PL011.
 
+config PL01X_SERIAL
+	bool "ARM PL010 and PL011 driver"
+	depends on DM_SERIAL
+	help
+	  Select this to enable a UART for platforms using PL010 or PL011.
+
 config ROCKCHIP_SERIAL
 	bool "Rockchip on-chip UART support"
 	depends on DM_SERIAL && SPL_OF_PLATDATA