tridentfb: move global chip_id into structure

This patch moves the chip_id into tridentfb_par structure and removes global
chip_id related constants.

It also bumps version of the driver to 0.7.9

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>