ath79: Fix support for TP-LINK Archer C7 v2

ath79: Fix support for TP-LINK Archer C7 v2

Remove mdio1 and phy1 handle. AR8327N is controlled through mdio0.
Add gmac-config for Archer C7.
Remove ucidef_set_interfaces_lan_wan. They can be determined by config_generate automatically.

The following are for adding support for WDR4900 v2/Archer C7 v1 and other
devices that shared the same machine file in ar71xx:
Move mtd partitions to archer-c7-v2.dts. Only Archer C7 v2 has 16M flash.
Flash on Archer C7 v1/TL-WDR4900 v2 is 8M.
Add label for wlan leds. The default trigger for archer c7/wdr4900 is different.
Move wlan5g led to archer-c7-v2.dts. 5G led on WDR4900 is connected to ar9380.
Move rfkill definition to archer-c7-v2.dts. There is no such a button on wdr4900 v2.

Signed-off-by: Chuanhong Guo <gch981213@gmail.com>