mi: drop two useless conditions in miPointerSetPosition

pDev cannot be NULL here since fill_pointer_events is the only caller.
And if the screen is NULL, then the device tries to send events before it is
fully initialised. That certainly shouldn't happen and would be a bug
elsewhere.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Keith Packard <keithp@keithp.com>

mi/mipointer.c

@@ -575,13 +575,8 @@ miPointerSetPosition(DeviceIntPtr pDev, int mode, double *screenx,
 
     miPointerPtr pPointer;
 
-    if (!pDev)
-        return NULL;
-
     pPointer = MIPOINTER(pDev);
     pScreen = pPointer->pScreen;
-    if (!pScreen)
-        return NULL;            /* called before ready */
 
     x = trunc(*screenx);
     y = trunc(*screeny);