fb: drop defines that aren't used/necessary anymore.

This was generated by:
cd fb
coan source --replace -DFB_SCREEN_PRIVATE -DFB_24BIT -DFB_24_32BIT -DFB_SCREEN_PRIVATE -UFBNOPIXADDR -UFBNO24BIT -UFBNO24_32 *.[ch]

A follow up patch readds the FB_24_32BIT define for Intel UXA.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Keith Packard <keithp@keithp.com>

fb/fbpixmap.c

@@ -89,10 +89,8 @@ fbCreatePixmap (ScreenPtr pScreen, int width, int height, int depth,
 {
     int	bpp;
     bpp = BitsPerPixel (depth);
-#ifdef FB_SCREEN_PRIVATE
     if (bpp == 32 && depth <= 24)
 	bpp = fbGetScreenPrivate(pScreen)->pix32bpp;
-#endif
     return fbCreatePixmapBpp (pScreen, width, height, depth, bpp, usage_hint);
 }