net: phy: ti: Add lane swapping support in the DP83867 TI's PHY driver

net: phy: ti: Add lane swapping support in the DP83867 TI's PHY driver

This patch adds support for enabling or disabling the lane swapping
(called "port mirroring" in PHY's CFG4 register) feature of the DP83867
TI's PHY device.

One use case is when bootstrap configuration enables this feature (because
of e.g. LED_0 wrong wiring) so then one needs to disable it in software
(at u-boot/Linux).

Based on commit fc6d39c39581 ("net: phy: dp83867: Add lane swapping
support in the DP83867 TI's PHY driver") of mainline linux kernel.

Signed-off-by: Janine Hagemann <j.hagemann@phytec.de>
Acked-by: Lukasz Majewski <lukma@denx.de>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>