sunxi: Add Marsboard A10 support

This patch add support for Marsboard A10 board.

The Marsboard A10 is a A10 based development board with 1G RAM, 1G NAND,
micro SD card slot, SATA 2.0 socket, 10/100 ethernet, mini HDMI port,
1 USB OTG port and 2 USB 2.0 ports. Board does not use the AXP209 pmic,
it does not have a pmic at all.
Board also have 2 expansion 70 pin headers.

Signed-off-by: Aleksei Mamlin <mamlinav@gmail.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

board/sunxi/MAINTAINERS

@@ -83,3 +83,8 @@ LINKSPRITE-PCDUINO BOARD
 M:	Zoltan Herpai <wigyori@uid0.hu>
 S:	Maintained
 F:	configs/Linksprite_pcDuino_defconfig
+
+MARSBOARD-A10 BOARD
+M:	Aleksei Mamlin <mamlinav@gmail.com>
+S:	Maintained
+F:	configs/Marsboard_A10_defconfig

configs/Marsboard_A10_defconfig

+CONFIG_SPL=y
+CONFIG_SYS_EXTRA_OPTIONS="SUNXI_EMAC,AHCI,USB_EHCI"
+CONFIG_FDTFILE="sun4i-a10-marsboard.dtb"
++S:CONFIG_ARM=y
++S:CONFIG_ARCH_SUNXI=y
++S:CONFIG_MACH_SUN4I=y
++S:CONFIG_DRAM_CLK=360
++S:CONFIG_DRAM_ZQ=123
++S:CONFIG_DRAM_EMR1=0