The bootloader of a number of recent TP-Link devices does not properly
initialise the MT7621's internal switch when booting from flash. To
enable the mt7530 driver to clear the reset on the switch, the ramips
reset controller must be allowed to toggle these.
Backport upstream commit 3f9ef7785a9c from mips-next to allow control of
the "mcm" reset line.
Signed-off-by: Sander Vanheule <sander@svanheule.net>
