radv: add support for 32-bit pointers in user data SGPRs

radv: add support for 32-bit pointers in user data SGPRs

We still use 64-bit GPU pointers for all ring buffers because
llvm.amdgcn.implicit.buffer.ptr doesn't seem to support 32-bit
GPU pointers for now. This can be improved later anyways.

Vega10:
Totals from affected shaders:
SGPRS: 1008722 -> 1026710 (1.78 %)
VGPRS: 706580 -> 707136 (0.08 %)
Spilled SGPRs: 22555 -> 22209 (-1.53 %)
Spilled VGPRs: 75 -> 75 (0.00 %)
Code Size: 34819208 -> 35202140 (1.10 %) bytes
Max Waves: 175423 -> 175086 (-0.19 %)

Polaris10:
Totals from affected shaders:
SGPRS: 1029849 -> 1036517 (0.65 %)
VGPRS: 709984 -> 708872 (-0.16 %)
Spilled SGPRs: 22672 -> 22309 (-1.60 %)
Spilled VGPRs: 82 -> 66 (-19.51 %)
Scratch size: 76 -> 60 (-21.05 %) dwords per thread
Code Size: 34915336 -> 35309752 (1.13 %) bytes
Max Waves: 151221 -> 151677 (0.30 %)

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>