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/mips/mach-mtmips/mt7628/serial.c b/arch/mips/mach-mtmips/mt7628/serial.c
index a7d3247..e5f3f87 100644
--- a/arch/mips/mach-mtmips/mt7628/serial.c
+++ b/arch/mips/mach-mtmips/mt7628/serial.c
@@ -11,7 +11,7 @@
 
 void mtmips_spl_serial_init(void)
 {
-#ifdef CONFIG_SPL_SERIAL_SUPPORT
+#ifdef CONFIG_SPL_SERIAL
 	void __iomem *base = ioremap_nocache(SYSCTL_BASE, SYSCTL_SIZE);
 
 #if CONFIG_CONS_INDEX == 1
@@ -30,5 +30,5 @@
 		      1 << SPIS_MODE_S);
 #endif /* CONFIG_SPL_UART2_SPIS_PINMUX */
 #endif /* CONFIG_CONS_INDEX */
-#endif /* CONFIG_SPL_SERIAL_SUPPORT */
+#endif /* CONFIG_SPL_SERIAL */
 }