drm/amdkfd: use allowed domain for vmbo validation

Fixes handling when page tables are in system memory.

v3: remove struct amdgpu_vm_parser.
v2: remove unwanted variable.
    change amdgpu_amdkfd_validate instead of amdgpu_amdkfd_bo_validate.

Signed-off-by: Nirmoy Das <nirmoy.das@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>