drm/amdgpu: add defines for DF and TCP Hashing

On Arcturus, we need TC channel hashing, which is set by the
driver, to match DF hashing, which is set by VBIOS. To match
these, we plan to query the DF information and then properly
set the TC configuration bits to match them.

This patch adds the required fields to register definitions
in preparation for a future patch which will use them.

Signed-off-by: Joseph Greathouse <Joseph.Greathouse@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>