sisfb: delete redudant #define SIS_LINUX_KERNEL
It's not needed anymore with SIS_XORG_XF86 gone.
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: Thomas Winischhofer <thomas@winischhofer.net>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
authored by Aaro Koskinen and committed by Paul Mundt b6c30ca6 e7d828ab