libflash: Fix pflash -i

pflash -i is currently broken due to this commit

  commit 602dee4
  Author: Cyril Bur <[email protected]>
  libflash/libffs: Rework libffs

It's output doesn't correctly detect the last partition and continues
printing forever.

This fixes it by returning null when we don't find a partition in
ffs_get_part().

Signed-off-by: Michael Neuling <[email protected]>
Acked-by: Cyril Bur <[email protected]>
Signed-off-by: Stewart Smith <[email protected]>

Author: mikey

libflash/libffs.c

@@ -187,9 +187,10 @@ static struct ffs_entry *ffs_get_part(struct ffs_handle *ffs, uint32_t index)
 
 	list_for_each(&ffs->hdr.entries, ent, list)
 		if (i++ == index)
-			break;
+			return ent;
 
-	return ent;
+	/* Didn't find partition */
+	return NULL;
 }
 
 bool has_ecc(struct ffs_entry *ent)