fastboot: sparse: implement reserve()

In order to process the CHUNK_TYPE_DONT_CARE properly, there is
a requirement to be able to 'reserve' a specified number of blocks
in the storage media. Because of the special handling of "bad blocks"
in NAND devices, this is implemented in a storage abstraction function.

Signed-off-by: Steve Rae <srae@broadcom.com>
Reviewed-by: Maxime Ripard <maxime.ripard@free-electrons.com>
diff --git a/common/image-sparse.c b/common/image-sparse.c
index b36703b..9632c6f 100644
--- a/common/image-sparse.c
+++ b/common/image-sparse.c
@@ -1,3 +1,4 @@
+
 /*
  * Copyright (c) 2009, Google Inc.
  * All rights reserved.
@@ -210,10 +211,8 @@
 			break;
 
 		case CHUNK_TYPE_DONT_CARE:
-#ifdef CONFIG_FASTBOOT_FLASH_MMC_DEV
-			blk += blkcnt;
+			blk += info->reserve(info, blk, blkcnt);
 			total_blocks += chunk_header->chunk_sz;
-#endif
 			break;
 
 		case CHUNK_TYPE_CRC32: