aco: increase global_load_params.max_const_offset_plus_one

aco: increase global_load_params.max_const_offset_plus_one

The callback now supports this. This shouldn't have any effect yet except
on GFX6 with 12 byte loads.

fossil-db (Pitcairn):
Totals from 246 (0.18% of 135668) affected shaders:
VGPRs: 14684 -> 14768 (+0.57%); split: -0.44%, +1.01%
CodeSize: 1765792 -> 1738040 (-1.57%)
Instrs: 344605 -> 340055 (-1.32%)
Latency: 4892904 -> 4861942 (-0.63%)
InvThroughput: 2479599 -> 2446070 (-1.35%)
VClause: 8782 -> 8735 (-0.54%)
SClause: 9854 -> 9853 (-0.01%)
Copies: 47327 -> 45401 (-4.07%); split: -4.08%, +0.01%

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14124>