staging: lustre/obdclass/acl: remove unused variable

lustre_ext_acl_xattr_reduce_space() declares old_size, but never uses it
and gcc 5.x likes to complain about this, so remove it as it's not used
at all.

Cc: Oleg Drokin <oleg.drokin@intel.com>
Cc: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/obdclass/acl.c

@@ -120,7 +120,6 @@ static int lustre_ext_acl_xattr_reduce_space(ext_acl_xattr_header **header,
 {
 	int ext_count = le32_to_cpu((*header)->a_count);
 	int ext_size = CFS_ACL_XATTR_SIZE(ext_count, ext_acl_xattr);
-	int old_size = CFS_ACL_XATTR_SIZE(old_count, ext_acl_xattr);
 	ext_acl_xattr_header *new;
 
 	if (unlikely(old_count <= ext_count))