Correct SPL uses of CMD_SF

This converts 2 usages of this option to the non-SPL form, since there is
no SPL_CMD_SF defined in Kconfig

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/environment/distro/sf.h b/include/environment/distro/sf.h
index 62624d5..ee48a8a 100644
--- a/include/environment/distro/sf.h
+++ b/include/environment/distro/sf.h
@@ -8,7 +8,7 @@
 #ifndef __DISTRO_SF_CONFIG_H
 #define __DISTRO_SF_CONFIG_H
 
-#if CONFIG_IS_ENABLED(CMD_SF)
+#if IS_ENABLED(CONFIG_CMD_SF)
 #define BOOTENV_SHARED_SF(devtypel)				\
 	#devtypel "_boot="					\
 	"if " #devtypel " probe ${busnum}; then "		\