avr32: factor out cpu_mmc_init()

cpu_mmc_init() is required by the init sequence to have a working MMC interface
on avr32. This will not be included in the binary if we omit the avr32 board.c
when building the generic board.

Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>
diff --git a/arch/avr32/cpu/mmc.c b/arch/avr32/cpu/mmc.c
new file mode 100644
index 0000000..b7213e4
--- /dev/null
+++ b/arch/avr32/cpu/mmc.c
@@ -0,0 +1,16 @@
+/*
+ * Copyright (C) 2004-2006 Atmel Corporation
+ * Copyright (C) 2015 Andreas Bießmann <andreas.devel@googlmail.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+#include <common.h>
+#include <atmel_mci.h>
+#include <asm/arch/hardware.h>
+
+/* provide cpu_mmc_init, to overwrite provide board_mmc_init */
+int cpu_mmc_init(bd_t *bd)
+{
+	/* This calls the atmel_mci_init in gen_atmel_mci.c */
+	return atmel_mci_init((void *)ATMEL_BASE_MMCI);
+}