dm: mmc: Support erase

At present erase is not suported with CONFIG_DM_OPS. Add it so that MMC
devices can be erased.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/mmc/mmc_private.h b/drivers/mmc/mmc_private.h
index d8b399e..03bf24d 100644
--- a/drivers/mmc/mmc_private.h
+++ b/drivers/mmc/mmc_private.h
@@ -29,15 +29,15 @@
 #endif
 
 #if !(defined(CONFIG_SPL_BUILD) && !defined(CONFIG_SPL_SAVEENV))
-unsigned long mmc_berase(struct blk_desc *block_dev, lbaint_t start,
-			 lbaint_t blkcnt);
 
 #ifdef CONFIG_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);
 #else
 ulong mmc_bwrite(struct blk_desc *block_dev, lbaint_t start, lbaint_t blkcnt,
 		 const void *src);
+ulong mmc_berase(struct blk_desc *block_dev, lbaint_t start, lbaint_t blkcnt);
 #endif
 
 #else /* CONFIG_SPL_BUILD and CONFIG_SPL_SAVEENV is not defined */