arm: socfpga: spl: Add support for booting from SD/MMC

Add code and configuration options to support booting from RAW
SD/MMC card as well as for ext4/vfat filesystems. Enable support
for booting from SD/MMC card, but don't enable the filesystem
support just yet to retain compatibility with old SoCFPGA card
format.

Signed-off-by: Marek Vasut <marex@denx.de>

configs/socfpga_arria5_defconfig

@@ -7,3 +7,5 @@ CONFIG_SPL=y
 # CONFIG_CMD_FLASH is not set
 CONFIG_OF_CONTROL=y
 CONFIG_SPI_FLASH=y
+CONFIG_SPL_DM=y
+CONFIG_SPL_MMC_SUPPORT=y

configs/socfpga_cyclone5_defconfig

@@ -9,3 +9,5 @@ CONFIG_OF_CONTROL=y
 CONFIG_SPI_FLASH=y
 CONFIG_NETDEVICES=y
 CONFIG_ETH_DESIGNWARE=y
+CONFIG_SPL_DM=y
+CONFIG_SPL_MMC_SUPPORT=y

configs/socfpga_socrates_defconfig

@@ -6,7 +6,8 @@ CONFIG_SPL=y
 # CONFIG_CMD_IMLS is not set
 # CONFIG_CMD_FLASH is not set
 CONFIG_OF_CONTROL=y
-CONFIG_SPL_DISABLE_OF_CONTROL=y
 CONFIG_SPI_FLASH=y
 CONFIG_NETDEVICES=y
 CONFIG_ETH_DESIGNWARE=y
+CONFIG_SPL_DM=y
+CONFIG_SPL_MMC_SUPPORT=y