viafb: remove duplicated CX700 register init

The current code initializes the register for CX700 chips 2 times due to a
missing break as discovered by Harald Welte.

As CX700 and VX800 have exactly the same register initialization we can
use one for both to avoid duplicated code.

As this is a pure code cleanup no measurable runtime effects are expected.

Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Scott Fang <ScottFang@viatech.com.cn>
Cc: Joseph Chan <JosephChan@via.com.tw>
Cc: Harald Welte <laforge@gnumonks.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>