Rename SPL_POWER_SUPPORT to SPL_POWER

Rename this option so that CONFIG_IS_ENABLED can be used with it.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
diff --git a/configs/am335x_sl50_defconfig b/configs/am335x_sl50_defconfig
index 3df8c97..928d222 100644
--- a/configs/am335x_sl50_defconfig
+++ b/configs/am335x_sl50_defconfig
@@ -32,7 +32,7 @@
 CONFIG_SPL_NET_SUPPORT=y
 CONFIG_SPL_NET_VCI_STRING="AM335x U-Boot SPL"
 CONFIG_SPL_OS_BOOT=y
-CONFIG_SPL_POWER_SUPPORT=y
+CONFIG_SPL_POWER=y
 CONFIG_SPL_WATCHDOG_SUPPORT=y
 CONFIG_SPL_YMODEM_SUPPORT=y
 CONFIG_CMD_SPL=y