spl: ram: Convert to CONFIG_IS_ENABLED

This patch is a preparation for adding TPL support for RAM loading.
CONFIG_IS_ENABLED allows for proper handling of the U-Boot/SPL/TPL
differences in config symbol names.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Tom Rini <trini@konsulko.com>

common/spl/spl_ram.c

@@ -36,7 +36,7 @@ static int spl_ram_load_image(struct spl_image_info *spl_image,
 
 	header = (struct image_header *)CONFIG_SPL_LOAD_FIT_ADDRESS;
 
-#if defined(CONFIG_SPL_DFU_SUPPORT)
+#if CONFIG_IS_ENABLED(DFU_SUPPORT)
 	if (bootdev->boot_device == BOOT_DEVICE_DFU)
 		spl_dfu_cmd(0, "dfu_alt_info_ram", "ram", "0");
 #endif
@@ -74,10 +74,10 @@ static int spl_ram_load_image(struct spl_image_info *spl_image,
 
 	return 0;
 }
-#if defined(CONFIG_SPL_RAM_DEVICE)
+#if CONFIG_IS_ENABLED(RAM_DEVICE)
 SPL_LOAD_IMAGE_METHOD("RAM", 0, BOOT_DEVICE_RAM, spl_ram_load_image);
 #endif
-#if defined(CONFIG_SPL_DFU_SUPPORT)
+#if CONFIG_IS_ENABLED(DFU_SUPPORT)
 SPL_LOAD_IMAGE_METHOD("DFU", 0, BOOT_DEVICE_DFU, spl_ram_load_image);
 #endif