drm/amdgpu: Enable seq64 manager and fix bugs

- Enable the seq64 mapping sequence.
- Fix wflinfo va conflict and other bugs.

v1:
- The seq64 area needs to be included in the AMDGPU_VA_RESERVED_SIZE
otherwise the areas will conflict with user space allocations (Alex)

- It needs to be mapped read only in the user VM (Alex)

v2:
- Instead of just one define for TOP/BOTTOM
reserved space separate them into two (Christian)

- Fix the CPU and VA calculations and while at it
also cleanup error handling and kerneldoc (Christian)

Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>

drm/amdgpu: Implement a new 64bit sequence memory driver

Developed a new driver which allocates a 64bit memory on
each request in sequence order. At the moment, user queue
fence memory is the main consumer of this seq64 driver.

v2: Worked on review comments from Christian for the following
modifications

- Move driver name from "semaphore" to "seq64"
- Remove unnecessary PT/PD mapping
- Move enable_mes check into init/fini functions.

v3: Worked on review comments from Christian

- drop enable_mes check
- use DECLARE_BITMAP for bit array
- added kerneldoc for seq64

v4: Worked on review comments from Christian
- Rename amdgpu_seq64_get name with amdgpu_seq64_alloc

v5: Worked on review comments from Christian
- Fix seq64 lockdep warning
- move fpriv->seq64_va check into amdgpu_seq64_unmap()
- make the function amdgpu_seq64_unmap() return as void.
- reserve the buffers as not interruptible.

v6: port to drm_exec (Alex)
v7: disable for now (Arun)

Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>