This would normally return the same values the core RandR code passed to
xf86RandR12CrtcSetGamma before, which is rather pointless. The only
possible exception would be if a driver tried initializing
crtc->gamma_red/green/blue to reflect the hardware LUT state on startup,
but that can't work correctly if whatever set the LUT before the server
started was running at a different depth.
Even the pointless round-trip case will no longer work with the
following change.
Reviewed-by: Keith Packard <keithp@keithp.com>