Blackfin: bf527-ad7160-eval: convert from old style MMR macros

The old MMR defines are being scrubbed, so convert the driver to use the
new standard helper macros.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

board/bf527-ad7160-eval/bf527-ad7160-eval.c

@@ -20,6 +20,6 @@ int checkboard(void)
 int misc_init_r(void)
 {
 	/* CLKIN Buffer Output Enable */
-	*pVR_CTL |= CLKBUFOE;
+	bfin_write_VR_CTL(bfin_read_VR_CTL() | CLKBUFOE);
 	return 0;
 }