Slightly change the API glamor_egl_init,
as this initialization is to initialize the display not
the screen, we should call it in xxx_preinit rather
than xxxScreenInit(). we change the input parameter as
below, as in preInit, the screen may not be allocated
at all. And in glamor_egl_init, it will not call
glamor_init. Driver should call glamor_init at
screen_init stage.

Signed-off-by: Zhigang Gong <zhigang.gong@linux.intel.com>