radv: Use correct vgpr_comp_cnt for VS if both prim_id and instance_id are needed.
Should take the max of the 2.
Fixes: ea337c8b "radv/gfx10: fix VS input VGPRs with the legacy path"
Should take the max of the 2.
Fixes: ea337c8b "radv/gfx10: fix VS input VGPRs with the legacy path"