dt-bindings: usb: Add new compatible string for AM64 SoC

Add compatible string in j721e-usb binding file as the same USB subsystem
is present in AM64.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Link: https://lore.kernel.org/r/20201215042549.7956-1-a-govindraju@ti.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>