drm/amdgpu: create kernel doorbell pages
This patch:
- creates a doorbell page for graphics driver usages.
- adds a few new varlables in adev->doorbell structure to
keep track of kernel's doorbell-bo.
- removes the adev->doorbell.ptr variable, replaces it with
kernel-doorbell-bo's cpu address.
V2: - Create doorbell BO directly, no wrappe functions (Alex)
- no additional doorbell structure (Alex, Christian)
- Use doorbell_cpu_ptr, remove ioremap (Christian, Alex)
- Allocate one extra page of doorbells for MES (Alex)
V4: Move MES doorbell base init into MES related patch (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>