luci-app-mwan3: Remove unnecessary dependency
luci-app-mwan3: Remove unnecessary dependency

There is no need to depend on luci-app-firewall, so remove the dependency.

I have examined the code and cannot see any reason for the dependency
and I have built a router with luci-app-mwan3, and without firewall,
luci-app-firewall and it all functions just fine.

Signed-off-by: Brian J. Murrell <760e7dab2836853c63805033e514668301fa9c47@interlinx.bc.ca>
lbthomsen/openwrt-luci,tobiaswaldvogel/luci,rogerpueyo/luci,lbthomsen/openwrt-luci,lbthomsen/openwrt-luci,hnyman/luci,rogerpueyo/luci,openwrt/luci,tobiaswaldvogel/luci,hnyman/luci,rogerpueyo/luci,lbthomsen/openwrt-luci,hnyman/luci,openwrt/luci,rogerpueyo/luci,lbthomsen/openwrt-luci,openwrt/luci,tobiaswaldvogel/luci,hnyman/luci,openwrt/luci,openwrt/luci,openwrt/luci,tobiaswaldvogel/luci,hnyman/luci,tobiaswaldvogel/luci,lbthomsen/openwrt-luci,rogerpueyo/luci,tobiaswaldvogel/luci,rogerpueyo/luci,lbthomsen/openwrt-luci,rogerpueyo/luci,openwrt/luci,hnyman/luci,hnyman/luci,lbthomsen/openwrt-luci,rogerpueyo/luci,hnyman/luci,tobiaswaldvogel/luci,tobiaswaldvogel/luci,openwrt/luci