staging/xgifb: Remove unnecessary cases in XGINew_SenseLCD

The switch statement sets the temp value to zero for certain cases and
leaves it untouched for other cases -> all these other cases can be
combined in the default case.

Since an empty case containing only a break, it can be removed.

The patch also removes the if statement, as it uses the same value as the switch
for comparison, and includes the code into the switch.

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>