gm107/ir: make use of IMUL32I for all immediates
IMUL only allows to emit 19-bits immediates. This is similar to d3076802 which fixed the same thing for the GK110 emitter. Signed-off-by:Samuel Pitoiset <samuel.pitoiset@gmail.com> Reviewed-by:
Ilia Mirkin <imirkin@alum.mit.edu> Cc: <mesa-stable@lists.freedesktop.org> (cherry picked from commit b84c9758)