serial: Rename SERIAL_SUPPORT to SERIAL

Rename these options so that CONFIG_IS_ENABLED can be used with them.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/Kconfig b/arch/Kconfig
index 507ebf7..382dd6e 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -120,7 +120,7 @@
 	imply SPL_OF_CONTROL
 	imply SPL_LIBCOMMON_SUPPORT
 	imply SPL_LIBGENERIC_SUPPORT
-	imply SPL_SERIAL_SUPPORT
+	imply SPL_SERIAL
 	imply SPL_TIMER
 
 config SANDBOX
@@ -259,7 +259,7 @@
 	imply SPL_PINCTRL
 	imply SPL_LIBCOMMON_SUPPORT
 	imply SPL_LIBGENERIC_SUPPORT
-	imply SPL_SERIAL_SUPPORT
+	imply SPL_SERIAL
 	imply SPL_SPI_FLASH_SUPPORT
 	imply SPL_SPI_SUPPORT
 	imply SPL_OF_CONTROL
@@ -273,7 +273,7 @@
 	imply TPL_PINCTRL
 	imply TPL_LIBCOMMON_SUPPORT
 	imply TPL_LIBGENERIC_SUPPORT
-	imply TPL_SERIAL_SUPPORT
+	imply TPL_SERIAL
 	imply TPL_OF_CONTROL
 	imply TPL_TIMER
 	imply TPL_REGMAP