arm: dts: k3-am642-*-evm: Add USB support

arm: dts: k3-am642-*-evm: Add USB support

AM64 EVM board has a micro USB 2.0 AB connector and the USB0_VBUS is
connected with a resistor divider in between. USB0_DRVVBUS pin is muxed
between USB0_DRVVBUS and GPIO1_79 signals.

Add the corresponding properties and set the pinmux mode for USB subsystem
in the evm dts file.

Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Link: https://lore.kernel.org/r/20210604163043.12811-7-a-govindraju@ti.com