usb: dwc3: add delay phy power change quirk

This patch adds delay PHY power change from P0 to P1/P2/P3 when link state
changing from U0 to U1/U2/U3 respectively, and some special platforms can
configure that if it is needed.

[ balbi@ti.com : added DeviceTree binding documentation ]

Signed-off-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt b/Documentation/devicetree/bindings/usb/dwc3.txt
index 4c77ed6..a2598d3 100644
--- a/Documentation/devicetree/bindings/usb/dwc3.txt
+++ b/Documentation/devicetree/bindings/usb/dwc3.txt
@@ -24,6 +24,8 @@
 			P1/P2/P3 transition sequence.
  - snps,del_p1p2p3_quirk: when set core will delay P1/P2/P3 until a certain
 			amount of 8B10B errors occur.
+ - snps,del_phy_power_chg_quirk: when set core will delay PHY power change
+			from P0 to P1/P2/P3.
 
 This is usually a subnode to DWC3 glue to which it is connected.