evas-drm: Remove improper EINA_UNUSED for function parameter

'fd' is actually used in the call to WaitVBlank, so do not mark it as
EINA_UNUSED

Signed-off-by: Chris Michael <cpmichael@osg.samsung.com>

src/modules/evas/engines/drm/evas_outbuf.c

@@ -48,7 +48,7 @@ _outbuf_tick_source_set(Outbuf *ob)
 }
 
 static void
-_outbuf_tick_schedule(int fd EINA_UNUSED, void *data)
+_outbuf_tick_schedule(int fd, void *data)
 {
    if (!ticking) return;