brcm47xx: handle return values of cfe_env_get() correctly.

This closes #12746.


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@35622 3c298f89-4303-0410-b956-a3cf2f4a3e73
brcm47xx:  fix network config on simpleshare 

The included patch will generate a correct network configuration on the simpletech simpleshare.

Thank you for the patch Will Holmes (RealOpty)

This closes #12361.


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@35623 3c298f89-4303-0410-b956-a3cf2f4a3e73