drm/amdgpu: remove the ring param from ttm functions

drm/amdgpu: remove the ring param from ttm functions

With the removal of the direct_submit argument, the ring param
becomes useless: the jobs are always submitted to buffer_funcs_ring.

Some functions are getting an amdgpu_device argument since they
were getting it from the ring arg.

---
v4: remove adev param from amdgpu_ttm_map_buffer
---

Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Acked-by: Felix Kuehling <felix.kuehling@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>