mips: mt76xx: linkit: Add mtd command support

The new mtd is very useful so let's enable it on the LinkIt Smart
7688 as well.
Signed-off-by: NStefan Roese <sr@denx.de>
Cc: Jiri Kastner <cz172638@gmail.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>

configs/linkit-smart-7688-ram_defconfig

@@ -20,6 +20,7 @@ CONFIG_CMD_MEMINFO=y
 # CONFIG_CMD_FLASH is not set
 CONFIG_CMD_GPIO=y
 # CONFIG_CMD_LOADS is not set
+CONFIG_CMD_MTD=y
 CONFIG_CMD_SF=y
 CONFIG_CMD_SPI=y
 CONFIG_CMD_DHCP=y

configs/linkit-smart-7688_defconfig

@@ -24,6 +24,7 @@ CONFIG_CMD_MEMINFO=y
 # CONFIG_CMD_FLASH is not set
 CONFIG_CMD_GPIO=y
 # CONFIG_CMD_LOADS is not set
+CONFIG_CMD_MTD=y
 CONFIG_CMD_SF=y
 CONFIG_CMD_SPI=y
 CONFIG_CMD_DHCP=y