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/common/Makefile b/common/Makefile
index 9063ed9..fb0256b 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -88,9 +88,9 @@
 obj-$(CONFIG_BOUNCE_BUFFER) += bouncebuf.o
 ifdef CONFIG_SPL_BUILD
 ifdef CONFIG_TPL_BUILD
-obj-$(CONFIG_TPL_SERIAL_SUPPORT) += console.o
+obj-$(CONFIG_TPL_SERIAL) += console.o
 else
-obj-$(CONFIG_SPL_SERIAL_SUPPORT) += console.o
+obj-$(CONFIG_SPL_SERIAL) += console.o
 endif
 else
 obj-y += console.o