xfs: split remote attr setting out from replace path
When we set a new xattr, we have three exit paths:
1. nothing else to do
2. allocate and set the remote xattr value
3. perform the rest of a replace operation
Currently we push both 2 and 3 into the same state, regardless of
whether we just set a remote attribute or not. Once we've set the
remote xattr, we have two exit states:
1. nothing else to do
2. perform the rest of a replace operation
Hence we can split the remote xattr allocation and setting into
their own states and factor it out of xfs_attr_set_iter() to further
clean up the state machine and the implementation of the state
machine.
Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Allison Henderson<allison.henderson@oracle.com> Reviewed-by: Dave Chinner <david@fromorbit.com> Signed-off-by: Dave Chinner <david@fromorbit.com>