afs: use correct afs_call_type in yfs_fs_store_opaque_acl2

It seems that 'yfs_RXYFSStoreOpaqueACL2' should be use in
yfs_fs_store_opaque_acl2().

Fixes: f5e45463 ("afs: Implement YFS ACL setting")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David Howells <dhowells@redhat.com>