tree: Rename the header and defines

The sunxi_cedrus.h header contains a bunch of defines prefixed with
SUNXI_CEDRUS.

As part as the ongoing migration to a more generic name, change that prefix
for V4L2_REQUEST, and the header file to request.h

Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>

src/context.c

@@ -25,7 +25,7 @@
 
 #include "context.h"
 #include "config.h"
-#include "sunxi_cedrus.h"
+#include "request.h"
 #include "surface.h"
 
 #include <stdlib.h>