doc: dt-binding: ci-hdrc-imx: add TPL support

TPL (Targeted Peripheral List) is needed for targets host
(OTG and Embedded Hosts) for usb certification and other
vendor specific requirements.

Signed-off-by: Peter Chen <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Documentation/devicetree/bindings/usb/ci-hdrc-imx.txt

···
 - disable-over-current: disable over current detect
 - external-vbus-divider: enables off-chip resistor divider for Vbus
 - maximum-speed: limit the maximum connection speed to "full-speed".
+- tpl-support: TPL (Targeted Peripheral List) feature for targeted hosts
 
 Examples:
 usb@02184000 { /* USB OTG */
···
 	disable-over-current;
 	external-vbus-divider;
 	maximum-speed = "full-speed";
+	tpl-support;
 };