staging: dt-bindings: wilc1000: add optional rtc_clk property

Add bindings for optional rtc clock pin.

Signed-off-by: Eugen Hristev <[e-mail]>
Acked-by: Ajay Singh <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/wilc1000/microchip,wilc1000,sdio.txt

···
 
 Optional:
 - bus-width	:	Number of data lines wired up the slot. Default 1 bit.
-
+- rtc_clk	:	Clock connected on the rtc clock line. Must be assigned
+			a frequency with assigned-clocks property, and must be
+			connected to a clock provider.
 
 Examples:
 mmc1: mmc@fc000000 {
···
 		wilc_sdio@0 {
 			compatible = "microchip,wilc1000-sdio";
 			irq-gpios = <&pioC 27 0>;
+			clocks = <&pck1>;
+			clock-names = "rtc_clk";
+			assigned-clocks = <&pck1>;
+			assigned-clock-rates = <32768>;
 			status = "okay";
 			reg = <0>;
 			bus-width = <4>;

drivers/staging/wilc1000/microchip,wilc1000,spi.txt

···
 - reg			: Chip select address of device
 - irq-gpios		: Connect to a host IRQ
 
+Optional:
+- rtc_clk	:	Clock connected on the rtc clock line. Must be assigned
+			a frequency with assigned-clocks property, and must be
+			connected to a clock provider.
 
 Examples:
 
···
 			spi-max-frequency = <48000000>;
 			reg = <0>;
 			irq-gpios = <&pioC 27 0>;
+			clocks = <&pck1>;
+			clock-names = "rtc_clk";
+			assigned-clocks = <&pck1>;
+			assigned-clock-rates = <32768>;
 			status = "okay";
 		};
 };