bcma: add trivial GBIT MAC COMMON driver

GMAC COMMON core is present on BCM4706 and is used for example to access
board PHYs (PHYs can not be accessed directly using GBIT MAC core).

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/bcma/driver_gmac_cmn.c

@@ -0,0 +1,14 @@
+/*
+ * Broadcom specific AMBA
+ * GBIT MAC COMMON Core
+ *
+ * Licensed under the GNU/GPL. See COPYING for details.
+ */
+
+#include "bcma_private.h"
+#include <linux/bcma/bcma.h>
+
+void __devinit bcma_core_gmac_cmn_init(struct bcma_drv_gmac_cmn *gc)
+{
+	mutex_init(&gc->phy_mutex);
+}