dt-bindings: cadence-quadspi: add options reset property

The QSPI module can have an optional reset signals that will hold the
module in a reset state.

Signed-off-by: Dinh Nguyen <[e-mail]>
Signed-off-by: Tudor Ambarus <[e-mail]>

Documentation/devicetree/bindings/mtd/cadence-quadspi.txt

···
 		  (qspi_n_ss_out).
 - cdns,tslch-ns : Delay in nanoseconds between setting qspi_n_ss_out low
                   and first bit transfer.
+- resets	: Must contain an entry for each entry in reset-names.
+		  See ../reset/reset.txt for details.
+- reset-names	: Must include either "qspi" and/or "qspi-ocp".
 
 Example:
 
···
 		cdns,fifo-depth = <128>;
 		cdns,fifo-width = <4>;
 		cdns,trigger-address = <0x00000000>;
+		resets = <&rst QSPI_RESET>, <&rst QSPI_OCP_RESET>;
+		reset-names = "qspi", "qspi-ocp";
 
 		flash0: n25q00@0 {
 			...