arm: mvebu: Add SPL SDIO/MMC boot support

This patch adds basic SDIO/MMC booting support to MVEBU SoC's. Since
I don't know of a way to test the boot-device upon runtime, this patch
hardcodes the spl_boot_device instead.

Tested on Marvell DB-88F6820-GP board.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Luka Perkov <luka.perkov@sartura.hr>
Cc: Dirk Eibach <eibach@gdsys.de>

arch/arm/mach-mvebu/spl.c

@@ -14,10 +14,21 @@ DECLARE_GLOBAL_DATA_PTR;
 
 u32 spl_boot_device(void)
 {
-	/* Right now only booting via SPI NOR flash is supported */
+#if defined(CONFIG_SPL_SPI_FLASH_SUPPORT)
 	return BOOT_DEVICE_SPI;
+#endif
+#if defined(CONFIG_SPL_MMC_SUPPORT)
+	return BOOT_DEVICE_MMC1;
+#endif
 }
 
+#ifdef CONFIG_SPL_MMC_SUPPORT
+u32 spl_boot_mode(void)
+{
+	return MMCSD_MODE_RAW;
+}
+#endif
+
 void board_init_f(ulong dummy)
 {
 	/* Set global data pointer */