dm-cache: remove pointless error check

Smatch reported following:
'''
drivers/md/dm-cache-target.c:3204 parse_cblock_range() warn: sscanf doesn't return error codes
drivers/md/dm-cache-target.c:3217 parse_cblock_range() warn: sscanf doesn't return error codes
'''

Sscanf doesn't return negative values at all.

Signed-off-by: Dipendra Khadka <kdipendra88@gmail.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

drivers/md/dm-cache-target.c

@@ -3200,8 +3200,6 @@ static int parse_cblock_range(struct cache *cache, const char *str,
 	 * Try and parse form (ii) first.
 	 */
 	r = sscanf(str, "%llu-%llu%c", &b, &e, &dummy);
-	if (r < 0)
-		return r;
 
 	if (r == 2) {
 		result->begin = to_cblock(b);
@@ -3213,8 +3211,6 @@ static int parse_cblock_range(struct cache *cache, const char *str,
 	 * That didn't work, try form (i).
 	 */
 	r = sscanf(str, "%llu%c", &b, &dummy);
-	if (r < 0)
-		return r;
 
 	if (r == 1) {
 		result->begin = to_cblock(b);