ext2: remove double definitions of xattr macros

remove the definitions of macros:
XATTR_TRUSTED_PREFIX
XATTR_USER_PREFIX
since they are defined in linux/xattr.h

Signed-off-by: Shen Feng <shen@cn.fujitsu.com>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/ext2/xattr_security.c b/fs/ext2/xattr_security.c
index eaa23d2..70c0dbd 100644
--- a/fs/ext2/xattr_security.c
+++ b/fs/ext2/xattr_security.c
@@ -14,7 +14,7 @@
 ext2_xattr_security_list(struct inode *inode, char *list, size_t list_size,
 			 const char *name, size_t name_len)
 {
-	const int prefix_len = sizeof(XATTR_SECURITY_PREFIX)-1;
+	const int prefix_len = XATTR_SECURITY_PREFIX_LEN;
 	const size_t total_len = prefix_len + name_len + 1;
 
 	if (list && total_len <= list_size) {