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

Use kernel.h definition.

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/adfs/dir_fplus.c b/fs/adfs/dir_fplus.c
index d9e3bee..7673c1f 100644
--- a/fs/adfs/dir_fplus.c
+++ b/fs/adfs/dir_fplus.c
@@ -55,7 +55,7 @@
 	}
 
 	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 *),