dt-bindings: extcon: storage-cd-gpio: Remove card detect GPIO extcon

UFS card support is removed from Kona, thus storage card detect GPIO
based extcon support added for UFS card is no longer used. This change
reverts commit ea32f8eecb ("dt-bindings: extcon: storage-cd-gpio: add
storage card detect GPIO extcon").

Change-Id: Ia9f1a66685a5bae6cc79e248191c4546fa9b3cdc

bindings/extcon/extcon-storage-cd-gpio.txt

@@ -1,30 +0,0 @@
-Storage card detect GPIO based Extcon device
-
-This is a virtual device used to generate GPIO states from the GPIO ID pin
-connected to a GPIO pin.
-
-Required properties:
-- compatible: Should be "extcon-storage-cd-gpio"
-- extcon-id: The unique id of specific external connector.
-	     Valid range is 0 (EXTCON_NONE) to 63 (EXTCON_NUM).
-	     Refer include/linux/extcon.h for details.
-- gpio: Specify GPIO (see gpio binding)
-- irq-flags: interrupt flags (edge/level). Refer to "include/dt-bindings/interrupt-controller/irq.h"
-- pinctrl-names, pinctrl-0, pinctrl-1,.. pinctrl-n: Refer to "Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt"
-  for these optional properties
-
-Example:
-	extcon_storage_cd {
-		compatible = "extcon-storage-cd-gpio";
-		extcon-id = <62>; /* EXTCON_MECHANICAL */
-		gpio = <&tlmm 126 GPIO_ACTIVE_LOW>;
-		irq-flags = <IRQ_TYPE_EDGE_BOTH>;
-	}
-
-	&ufshc_card {
-		extcon = <&extcon_storage_cd>;
-	};
-
-	&sd_card {
-		extcon = <&extcon_storage_cd>;
-	};