dt-bindings: usb: Remove obsolete brcm,bcm3384-usb.txt

The "brcm,bcm3384-ohci" and "brcm,bcm3384-ehci" compatibles are already
documented in generic-ohci.yaml and generic-ehci.yaml, respectively, so
remove the old txt binding.
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230110-dt-usb-v3-1-5af0541fcf8c@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/usb/brcm,bcm3384-usb.txt

-* Broadcom USB controllers
-
-Required properties:
-- compatible: "brcm,bcm3384-ohci", "brcm,bcm3384-ehci"
-
-  These currently use the generic-ohci and generic-ehci drivers.  On some
-  systems, special handling may be needed in the following cases:
-
-  - Restoring state after systemwide power save modes
-  - Sharing PHYs with the USBD (UDC) hardware
-  - Figuring out which controllers are disabled on ASIC bondout variants