This patch:
- creates a new file for doorbell management.
- moves doorbell code from amdgpu_device.c to this file.
V2:
- remove doc from function declaration (Christian)
- remove 'device' from function names to make it consistent (Alex)
- add SPDX license identifier (Luben)
V3:
- change license to MIT license(Christian)
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian Koenig <christian.koenig@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Shashank Sharma <shashank.sharma@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
