drm/amdgpu: Drop concurrent GPU reset protection for device

Since now all GPU resets are serialzied there is no need for this.

This patch also reverts 'drm/amdgpu: race issue when jobs on 2 ring timeout'

Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://www.spinics.net/lists/amd-gfx/msg74119.html