block: genhd.h comment needs updating

The include/linux/genhd.h file, on line 338-352 declares some function
prototypes in which the comment on line 338 states that the definition of
these prototypes are to be found at drivers/block/genhd.c. The problem is
that genhd.c has been relocated to block/genhd.c. See attached patch to
correct this minor cosmetic typo.
Signed-off-by: Petros Koutoupis <pkoutoupis@hydrasystemsllc.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

include/linux/genhd.h

@@ -336,7 +336,7 @@ static inline void part_dec_in_flight(struct hd_struct *part)
 /* drivers/block/ll_rw_blk.c */
 extern void part_round_stats(int cpu, struct hd_struct *part);
 
-/* drivers/block/genhd.c */
+/* block/genhd.c */
 extern int get_blkdev_list(char *, int);
 extern void add_disk(struct gendisk *disk);
 extern void del_gendisk(struct gendisk *gp);