staging: xgifb: function prototype argument should also have an identifier name

function prototype argument 'struct vb_device_info *' and 'unsigned
long' should also have an identifier name.

Signed-off-by: Arushi Singhal <arushisinghal19971997@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>