fs/adfs/dir_fplus.c: use ARRAY_SIZE instead of sizeof/sizeof[0]

Use kernel.h definition.
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fs/adfs/dir_fplus.c

@@ -55,7 +55,7 @@ adfs_fplus_read(struct super_block *sb, unsigned int id, unsigned int sz, struct
 	}
 
 	size >>= sb->s_blocksize_bits;
-	if (size > sizeof(dir->bh)/sizeof(dir->bh[0])) {
+	if (size > ARRAY_SIZE(dir->bh)) {
 		/* this directory is too big for fixed bh set, must allocate */
 		struct buffer_head **bh_fplus =
 			kzalloc(size * sizeof(struct buffer_head *),