freedreno: Use Android's libsync instead of libdrm's.

This should be equivalent, given that we only support the DRM backend so
far, but we'll want to have the compatibility for future KGSL freedreno.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7227>

src/gallium/drivers/freedreno/freedreno_context.h

@@ -27,11 +27,10 @@
 #ifndef FREEDRENO_CONTEXT_H_
 #define FREEDRENO_CONTEXT_H_
 
-#include <libsync.h>
-
 #include "pipe/p_context.h"
 #include "indices/u_primconvert.h"
 #include "util/u_blitter.h"
+#include "util/libsync.h"
 #include "util/list.h"
 #include "util/slab.h"
 #include "util/u_string.h"

src/gallium/drivers/freedreno/freedreno_fence.c

@@ -24,8 +24,6 @@
  *    Rob Clark <robclark@freedesktop.org>
  */
 
-#include <libsync.h>
-
 #include "util/os_file.h"
 #include "util/u_inlines.h"