drm/amdgpu: Remove unnecessary TLB workaround (v2)

drm/amdgpu: Remove unnecessary TLB workaround (v2)

This workaround is better handled in user mode in a way that doesn't
require allocating extra memory and breaking userptr BOs.

The TLB bug is a performance bug, not a functional or security bug.
Hence it is safe to remove this kernel part of the workaround to
allow a better workaround using only virtual address alignments in
user mode.

v2: Removed VI_BO_SIZE_ALIGN definition

Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>