aco: don't expand smem/mubuf global loads

aco: don't expand smem/mubuf global loads

For example, dwordx3->dwordx4 or ubyte3->dwordx2.

Global loads don't have the bounds checking that buffer loads have that
makes this safe.

The alignment checks are added to global_load_callback() in case
byte_align_loads=false, align=1 and bytes_needed=3. Without them, the
callback will create a dword load.

fossil-db (Sienna Cichlid):
Totals from 267 (0.20% of 134621) affected shaders:
CodeSize: 1603352 -> 1606568 (+0.20%)
Instrs: 294946 -> 295482 (+0.18%); split: -0.00%, +0.18%
Latency: 2997003 -> 2997052 (+0.00%); split: -0.02%, +0.02%
InvThroughput: 526645 -> 526659 (+0.00%)
SClause: 9179 -> 9185 (+0.07%); split: -0.02%, +0.09%
Copies: 25363 -> 25375 (+0.05%); split: -0.08%, +0.13%
Branches: 8298 -> 8299 (+0.01%)

fossil-db (Polaris10):
Totals from 267 (0.20% of 135668) affected shaders:
CodeSize: 1636672 -> 1638756 (+0.13%); split: -0.00%, +0.13%
Instrs: 308484 -> 308733 (+0.08%); split: -0.01%, +0.09%
Latency: 3446045 -> 3446904 (+0.02%); split: -0.00%, +0.03%
InvThroughput: 1206722 -> 1206828 (+0.01%); split: -0.00%, +0.01%
SClause: 9308 -> 9311 (+0.03%); split: -0.08%, +0.11%
Copies: 36933 -> 36921 (-0.03%); split: -0.08%, +0.05%

fossil-db (Pitcairn):
Totals from 275 (0.20% of 135668) affected shaders:
SGPRs: 17616 -> 17520 (-0.54%); split: -0.64%, +0.09%
VGPRs: 15428 -> 15540 (+0.73%); split: -0.23%, +0.96%
CodeSize: 1885792 -> 1929120 (+2.30%); split: -0.00%, +2.30%
MaxWaves: 1284 -> 1285 (+0.08%)
Instrs: 368963 -> 376095 (+1.93%); split: -0.00%, +1.94%
Latency: 5122922 -> 5168398 (+0.89%); split: -0.01%, +0.90%
InvThroughput: 2562866 -> 2604279 (+1.62%)
VClause: 9268 -> 9296 (+0.30%); split: -0.13%, +0.43%
SClause: 10702 -> 10705 (+0.03%); split: -0.05%, +0.07%
Copies: 48620 -> 50629 (+4.13%); split: -0.08%, +4.21%

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>