mips: Add support for SoM "VoCore2".

Small patch to add support for VoCore/VoCore2 board.

VoCore is open hardware and runs OpenWrt/LEDE.
It has WIFI, USB, UART, 20+ GPIOs but is only one inch square.
It will help you to make a smart house, study embedded system
or even make the tiniest router in the world.

Details about this SoM can be found at "https://vocore.io/v2.html".

Signed-off-by: Mauro Condarelli <mc5686@mclink.it>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/arch/mips/mach-mtmips/Kconfig b/arch/mips/mach-mtmips/Kconfig
index 60cc0f8..737de2c 100644
--- a/arch/mips/mach-mtmips/Kconfig
+++ b/arch/mips/mach-mtmips/Kconfig
@@ -87,6 +87,15 @@
 	  SPI-NOR flash, 1 built-in switch with 5 ports, 1 UART, 1 USB host,
 	  1 SDXC, 1 PCIe socket and JTAG pins.
 
+config BOARD_VOCORE2
+	bool "VoCore2"
+	depends on SOC_MT7628
+	select SPL_SERIAL_SUPPORT
+	select SPL_UART2_SPIS_PINMUX
+	help
+	  VoCore VoCore2 board has a MT7628 SoC with 128 MiB of RAM
+	  and 16 MiB of flash (SPI).
+
 endchoice
 
 config SPL_UART2_SPIS_PINMUX
@@ -100,5 +109,6 @@
 source "board/gardena/smart-gateway-mt7688/Kconfig"
 source "board/mediatek/mt7628/Kconfig"
 source "board/seeed/linkit-smart-7688/Kconfig"
+source "board/vocore/vocore2/Kconfig"
 
 endmenu