arm64: dts: imx8mp: Adjust EQoS PHY address on i.MX8MP DHCOM

The current variant of the SoM has LAN8740Ai PHY connected to EQoS
strapped to MDIO address 0 , adjust the MDIO address to match the
hardware.

Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>