dfu: Make DFU support more SPL friendly

Do this by using $(SPL_) in Makefiles and CONFIG_IS_ENABLED in C code.
This ensures the files and features are only built into the right build
for which they are enabled. Using the macros to simplify this patch was
made possible by the config symbol rename done in the last patch.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Acked-by: Lukasz Majewski <lukma@denx.de>
diff --git a/include/dfu.h b/include/dfu.h
index fbe978a..9340a90 100644
--- a/include/dfu.h
+++ b/include/dfu.h
@@ -202,7 +202,7 @@
 int dfu_write_from_mem_addr(struct dfu_entity *dfu, void *buf, int size);
 
 /* Device specific */
-#ifdef CONFIG_DFU_MMC
+#if CONFIG_IS_ENABLED(DFU_MMC)
 extern int dfu_fill_entity_mmc(struct dfu_entity *dfu, char *devstr, char *s);
 #else
 static inline int dfu_fill_entity_mmc(struct dfu_entity *dfu, char *devstr,
@@ -213,7 +213,7 @@
 }
 #endif
 
-#ifdef CONFIG_DFU_NAND
+#if CONFIG_IS_ENABLED(DFU_NAND)
 extern int dfu_fill_entity_nand(struct dfu_entity *dfu, char *devstr, char *s);
 #else
 static inline int dfu_fill_entity_nand(struct dfu_entity *dfu, char *devstr,
@@ -224,7 +224,7 @@
 }
 #endif
 
-#ifdef CONFIG_DFU_RAM
+#if CONFIG_IS_ENABLED(DFU_RAM)
 extern int dfu_fill_entity_ram(struct dfu_entity *dfu, char *devstr, char *s);
 #else
 static inline int dfu_fill_entity_ram(struct dfu_entity *dfu, char *devstr,
@@ -235,7 +235,7 @@
 }
 #endif
 
-#ifdef CONFIG_DFU_SF
+#if CONFIG_IS_ENABLED(DFU_SF)
 extern int dfu_fill_entity_sf(struct dfu_entity *dfu, char *devstr, char *s);
 #else
 static inline int dfu_fill_entity_sf(struct dfu_entity *dfu, char *devstr,
@@ -259,7 +259,7 @@
  *
  * @return 0 on success, otherwise error code
  */
-#ifdef CONFIG_DFU_TFTP
+#if CONFIG_IS_ENABLED(DFU_TFTP)
 int dfu_tftp_write(char *dfu_entity_name, unsigned int addr, unsigned int len,
 		   char *interface, char *devstring);
 #else