[JFFS2][XATTR] remove typedef from posix_acl related definition.

jffs2_acl_header, jffs2_acl_entry and jffs2_acl_entry_short were redefined
with using 'struct' instead of 'typedef' in kernel implementation.

[1/10] jffs2-xattr-v5.1-01-remove_typedef_kernel.patch

Signed-off-by: KaiGai Kohei <kaigai@ak.jp.nec.com>