nir/idiv_const: optimize imod/irem

nir/idiv_const: optimize imod/irem

fossil-db changes (Sienna Cichlid):
Totals from 223 (0.15% of 150170) affected shaders:
CodeSize: 384564 -> 370824 (-3.57%)
Instrs: 74518 -> 71961 (-3.43%)
Latency: 351620 -> 344640 (-1.99%)
InvThroughput: 80122 -> 74846 (-6.58%)
VClause: 919 -> 920 (+0.11%)
SClause: 2879 -> 2877 (-0.07%); split: -0.10%, +0.03%
Copies: 3099 -> 3103 (+0.13%)

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12039>