dm: mmc: Allow disabling driver model in SPL

At present if U-Boot proper uses driver model for MMC, then SPL has to
also. While this is desirable, it places a significant barrier to moving
to driver model in some cases. For example, with a space-constrained SPL
it may be necessary to enable CONFIG_SPL_OF_PLATDATA which involves
adjusting some drivers.

Add new SPL versions of the options for DM_MMC, DM_MMC_OPS and BLK. By
default these follow their non-SPL versions, but this can be changed by
boards which need it.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/mmc/mmc_private.h b/drivers/mmc/mmc_private.h
index 03bf24d..1290eed 100644
--- a/drivers/mmc/mmc_private.h
+++ b/drivers/mmc/mmc_private.h
@@ -20,7 +20,7 @@
 void mmc_adapter_card_type_ident(void);
 #endif
 
-#ifdef CONFIG_BLK
+#if CONFIG_IS_ENABLED(BLK)
 ulong mmc_bread(struct udevice *dev, lbaint_t start, lbaint_t blkcnt,
 		void *dst);
 #else
@@ -30,7 +30,7 @@
 
 #if !(defined(CONFIG_SPL_BUILD) && !defined(CONFIG_SPL_SAVEENV))
 
-#ifdef CONFIG_BLK
+#if CONFIG_IS_ENABLED(BLK)
 ulong mmc_bwrite(struct udevice *dev, lbaint_t start, lbaint_t blkcnt,
 		 const void *src);
 ulong mmc_berase(struct udevice *dev, lbaint_t start, lbaint_t blkcnt);
@@ -44,7 +44,7 @@
 
 /* declare dummies to reduce code size. */
 
-#ifdef CONFIG_BLK
+#if CONFIG_IS_ENABLED(BLK)
 static inline unsigned long mmc_berase(struct udevice *dev,
 				       lbaint_t start, lbaint_t blkcnt)
 {