In some boards port 4 of mt7620 switch is powered down in bootloader
configuration as lan/wan package leak mitigation.
Reset ephy port 4 to default settings to power up the port.
Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>
[clarify issue in commit message]
Signed-off-by: Mathias Kresin <dev@kresin.me>