dt-bindings: usb: update snps,dwc3.yaml references

Changeset 389d7765 ("dt-bindings: usb: Convert DWC USB3 bindings to DT schema")
renamed: Documentation/devicetree/bindings/usb/dwc3.txt
to: Documentation/devicetree/bindings/usb/snps,dwc3.yaml.

Update its cross-references accordingly.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/97704f110f0282fb47eb85dea430cc94cfd93a4b.1610605373.git.mchehab+huawei@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/usb/dwc3-st.txt

@@ -31,7 +31,7 @@ See: Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
 Sub-nodes:
 The dwc3 core should be added as subnode to ST DWC3 glue as shown in the
 example below. The DT binding details of dwc3 can be found in:
-Documentation/devicetree/bindings/usb/dwc3.txt
+Documentation/devicetree/bindings/usb/snps,dwc3.yaml
 
 NB: The dr_mode property described in [1] is NOT optional for this driver, as the default value
 is "otg", which isn't supported by this SoC. Valid dr_mode values for dwc3-st are either "host"

Documentation/devicetree/bindings/usb/exynos-usb.txt

@@ -93,7 +93,7 @@ Sub-nodes:
 The dwc3 core should be added as subnode to Exynos dwc3 glue.
 - dwc3 :
    The binding details of dwc3 can be found in:
-   Documentation/devicetree/bindings/usb/dwc3.txt
+   Documentation/devicetree/bindings/usb/snps,dwc3.yaml
 
 Example:
 	usb@12000000 {

Documentation/devicetree/bindings/usb/omap-usb.txt

@@ -65,7 +65,7 @@ Sub-nodes:
 The dwc3 core should be added as subnode to omap dwc3 glue.
 - dwc3 :
    The binding details of dwc3 can be found in:
-   Documentation/devicetree/bindings/usb/dwc3.txt
+   Documentation/devicetree/bindings/usb/snps,dwc3.yaml
 
 omap_dwc3 {
 	compatible = "ti,dwc3";