viafb: remove lcdtbl.h

This patch moves the power on/off sequences to lcd.c as they are only
used there. This allows removing lcdtbl.h as the other stuff is not
used.

Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Joseph Chan <JosephChan@via.com.tw>