uboot-envtools: add support for Linksys EA6350v3

uboot-envtools: add support for Linksys EA6350v3

This commit adds support for the Linksys EA6350v3 device in the ipq40xx
target.

This is needed for uboot-envtools to access the environment. Without this
patch, the Linksys EA6350v3 will not be able to access the uboot
environment. As a side effect, the feature auto_recovery will make the
device unstable by switching between the latest and the current firmware.

Signed-off-by: Ryan Pannell <ryan@osukl.com>
Signed-off-by: Oever González <notengobattery@gmail.com>