Move the comphy handle property of the PCIe node from board specific
device tree files (EspressoBin and Turris Mox) to the generic
armada-37xx.dtsi.

This is correct since this is the only possible PCIe PHY configuration
on Armada 37xx, so when PCIe is enabled on any board, this handle is
correct.
Signed-off-by: NMarek Behún <marek.behun@nic.cz>
Tested-by: NTomasz Maciej Nowak <tmn505@gmail.com>
Acked-by: NThomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: NGregory CLEMENT <gregory.clement@bootlin.com>