[PATCH 8_9] Add block_write hook to block_dev_desc_t

Preparation for future patches which support block device writing
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>

include/part.h

@@ -45,6 +45,10 @@ typedef struct block_dev_desc {
 				      unsigned long start,
 				      lbaint_t blkcnt,
 				      unsigned long *buffer);
+	unsigned long	(*block_write)(int dev,
+				       unsigned long start,
+				       lbaint_t blkcnt,
+				       const void *buffer);
 }block_dev_desc_t;
 
 /* Interface types: */