i965: Fix multiplication of immediates on Cherryview/Broxton.

i965: Fix multiplication of immediates on Cherryview/Broxton.

Cherryview and Broxton don't support DW x DW multiplication.  We have
piles of code to handle this, but apparently weren't retyping in the
immediate case.

For example,
tests/spec/arb_tessellation_shader/execution/dvec3-vs-tcs-tes
makes the simulator angry about instructions such as:

   mul(8) r18<1>:D r10.0<8;8,1>:D 0x00000003:D

Just retype to W or UW.  It should be safe on all platforms.

Cc: "12.0" <mesa-stable@lists.freedesktop.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=95462
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>