radeon: add new firmware for SI and TN

This add firmware for the HD7xxx asics code-
named Southern Islands and the trinity APU code-
named Aruba.

It also updates the dates on the license info.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>