drm/gpuvm: Add DRM_GPUVA_OP_DRIVER

Add DRM_GPUVA_OP_DRIVER which allows driver to define their own gpuvm
ops. Useful for driver created ops which can be passed into the bind
software pipeline.

v3:
 - s/DRM_GPUVA_OP_USER/DRM_GPUVA_OP_DRIVER (Thomas)
 - Better commit message (Thomas)

Cc: Danilo Krummrich <dakr@redhat.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250306012657.3505757-14-matthew.brost@intel.com