drm/amdgpu: Move VM PTE MTYPE override to per-PTE granularity

drm/amdgpu: Move VM PTE MTYPE override to per-PTE granularity

Refactor the NUMA-aware MTYPE override for VM page table entries:

Move the override_vm_pte_flags call from the centralized
amdgpu_vm_pte_update_flags() into the individual CPU and SDMA update
backends, enabling per-PTE MTYPE override including for scattered
pages (pages_addr path).

Move APU, IP version, and direct-mapped eligibility checks from
runtime (gmc_v9_0_override_vm_pte_flags) to init time
(gmc_v9_0_set_gmc_funcs), to avoid repeated runtime checks on
every PTE update.

Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>