Use MI rasops_cmap, instead of MD-defined ANSI colormap.

Use MI rasops_cmap, instead of MD-defined ANSI colormap.

Note about workaround for 8bpp frame buffer:

Current LUNA wscons touches only first 4 planes (plane #0-#3), but
other program (e.g. mlterm-fb) can use all 8 planes on an 8bpp frame
buffer.  When such program exits, it may not clear all planes, so
there may be some visible garbage data on the other 4 planes (plane
#4-#7) when we use default 256 rasops_cmap directly.

We should manage all 8 planes on LUNA, but that will be too much
overhead for 16 colors wscons.  So, by repeating 16 colors in 256
colormap, we can ignore the values on the other 4 planes.

ok miod@