Allowing longer writes reduces the number of send messages needed
to support unaligned 4-component writes.
Note: nothing currently generates 8-component writes, so this change
makes "second_mask" code path in emit_urb_direct_writes and
emit_urb_indirect_writes_mod dead.
Reviewed-by: Caio Oliveira <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20858>
be82ed28f0