vga: remove unused static constant.
vga: remove unused static constant.

I'm a little baffled as to why I didn't get an unused code warning for
this, given how ridiculous my warning settings are.  Anyway, this
constant has been obsolete since 13 Dec 2013.

cbiffle/m4vgalib,cbiffle/m4vgalib,cbiffle/m4vgalib,cbiffle/m4vgalib