drm/vc4: Allow some more signals to be packed with uniform resets.

The intent was to make sure people don't sneak in a small immediate or
something to change the interpretation of the uniform update args, but
these signals are just fine.

Fixes a validation failure in the current X server on some Render
operation.

Signed-off-by: Eric Anholt <eric@anholt.net>
(cherry picked from commit 313a61d3)