broadcom/compiler: use nir_lower_undef_to_zero

broadcom/compiler: use nir_lower_undef_to_zero

total instructions in shared programs: 13731663 -> 13721549 (-0.07%)
instructions in affected programs: 98242 -> 88128 (-10.29%)
helped: 191
HURT: 131
Instructions are helped.

total threads in shared programs: 412272 -> 412296 (<.01%)
threads in affected programs: 24 -> 48 (100.00%)
helped: 12
HURT: 0
Threads are helped.

total uniforms in shared programs: 3780693 -> 3779137 (-0.04%)
uniforms in affected programs: 10564 -> 9008 (-14.73%)
helped: 114
HURT: 7
Uniforms are helped.

total max-temps in shared programs: 2319942 -> 2319528 (-0.02%)
max-temps in affected programs: 4191 -> 3777 (-9.88%)
helped: 113
HURT: 22
Max-temps are helped.

total sfu-stalls in shared programs: 31584 -> 31616 (0.10%)
sfu-stalls in affected programs: 217 -> 249 (14.75%)
helped: 51
HURT: 54
Inconclusive result (value mean confidence interval includes 0).

total inst-and-stalls in shared programs: 13763247 -> 13753165 (-0.07%)
inst-and-stalls in affected programs: 98719 -> 88637 (-10.21%)
helped: 187
HURT: 134
Inst-and-stalls are helped.

Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9681>