Correct SPL uses of FASTBOOT_FLASH_MMC

This converts 5 usages of this option to the non-SPL form, since there is
no SPL_FASTBOOT_FLASH_MMC defined in Kconfig

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
diff --git a/drivers/fastboot/fb_getvar.c b/drivers/fastboot/fb_getvar.c
index bcef8f8..de4879d 100644
--- a/drivers/fastboot/fb_getvar.c
+++ b/drivers/fastboot/fb_getvar.c
@@ -62,7 +62,7 @@
 		.variable = "has-slot",
 		.dispatch = getvar_has_slot
 #endif
-#if CONFIG_IS_ENABLED(FASTBOOT_FLASH_MMC)
+#if IS_ENABLED(CONFIG_FASTBOOT_FLASH_MMC)
 	}, {
 		.variable = "partition-type",
 		.dispatch = getvar_partition_type
@@ -99,7 +99,7 @@
 	struct disk_partition disk_part;
 	struct part_info *part_info;
 
-	if (CONFIG_IS_ENABLED(FASTBOOT_FLASH_MMC)) {
+	if (IS_ENABLED(CONFIG_FASTBOOT_FLASH_MMC)) {
 		r = fastboot_mmc_get_part_info(part_name, &dev_desc, &disk_part,
 					       response);
 		if (r >= 0 && size)