radv: tweak lower_shader_calls parameters

radv: tweak lower_shader_calls parameters

On Q2RTX shaders :

MaxWaves: 62 -> 69 (+11.29%)
Instrs: 41626 -> 41575 (-0.12%); split: -0.27%, +0.15%
CodeSize: 224960 -> 223740 (-0.54%); split: -0.62%, +0.08%
VGPRs: 800 -> 704 (-12.00%)
Scratch: 75776 -> 70656 (-6.76%)
Latency: 922219 -> 977997 (+6.05%)
InvThroughput: 212154 -> 201746 (-4.91%); split: -5.54%, +0.64%
VClause: 1120 -> 1155 (+3.12%); split: -1.88%, +5.00%
SClause: 1148 -> 1144 (-0.35%); split: -0.70%, +0.35%
Copies: 5840 -> 5788 (-0.89%); split: -0.94%, +0.05%
PreVGPRs: 753 -> 651 (-13.55%)

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Konstantin Seurer <konstantin.seurer@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16556>