staging: xgifb: vb_setmode: delete IF_DEF_HiVision checks

Code checking for IF_DEF_HiVision is only executed for chips < XG20,
and there IF_DEF_HiVision is always true, so the flag is redundant.

Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>