drm/amdgpu: Merge amdgpu_vm_set_pasid into amdgpu_vm_init

drm/amdgpu: Merge amdgpu_vm_set_pasid into amdgpu_vm_init

As KFD no longer uses a separate PASID, the global amdgpu_vm_set_pasid()function is no longer necessary.
Merge its functionality directly intoamdgpu_vm_init() to simplify code flow and eliminate redundant locking.

v2: remove superflous check
  adjust amdgpu_vm_fin and remove amdgpu_vm_set_pasid (Chritian)

v3: drop amdgpu_vm_assert_locked (Chritian)

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4614
Fixes: 59e4405e9ee2 ("drm/amdgpu: revert to old status lock handling v3")
Reviewed-by: Christian König <christian.koenig@amd.com>
Suggested-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Jesse Zhang <Jesse.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>