staging: xgifb: delete bogus video RAM configuration

The driver reconfigures DRAM size register to 8M (regardless what the
actual size was) once the init has been completed, overwriting the
correct value written during the early init. As a result if the driver
is unloaded and reloaded, the user will be limited to 8M video memory
and may lose some of the available video modes.

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