fs/block_dev.c: make sb_is_blkdev_sb return bool when CONFIG_BLOCK undefined

Currently when CONFIG_BLOCK is defined sb_is_blkdev_sb returns bool,
while when CONFIG_BLOCK is not defined it returns int. Let's keep
consistent to make sb_is_blkdev_sb return bool as well when CONFIG_BLOCK
isn't defined.

No functional change.
Signed-off-by: NYaowei Bai <baiyaowei@cmss.chinamobile.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

include/linux/fs.h

@@ -2291,9 +2291,9 @@ static inline void iterate_bdevs(void (*f)(struct block_device *, void *), void
 {
 }
 
-static inline int sb_is_blkdev_sb(struct super_block *sb)
+static inline bool sb_is_blkdev_sb(struct super_block *sb)
 {
-	return 0;
+	return false;
 }
 #endif
 extern int sync_filesystem(struct super_block *);