Bug#565313: dimmed screen with 16-bit depth using radeon driver

[Alexander Sosedkin]

Same regression for me, notebook is fujitsu p1120, video card is
reported as ATI Technologies Inc Radeon Mobility M6 LY.

Everything is dimmed and the color is definitely broken, looks like it
was been repacked from R5G6B5 to R8G8B8 without scaling it, so
11111 111111 11111 became 00011111 00111111 00011111. I may be wrong
though. Changing depth to 24 bit works for me.

Sorry for not attaching any logs or configs.