drm/amdgpu: add drm_file reference in userq_mgr

drm/amdgpu: add drm_file reference in userq_mgr

drm_file will be used in usermode queues code to
enable better process information in logging and hence
add drm_file part of the userq_mgr struct.

update the drm_file pointer in userq_mgr for each
amdgpu_driver_open_kms.

Signed-off-by: Sunil Khatri <sunil.khatri@amd.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>