dt: bindings: Add new regulator as optional property for WCN3990

Add an additional regulator supply as an optional
property for WCN3990.

Tested-on: WCN3990 hw1.0 SNOC WLAN.HL.3.1-01040-QCAHLSWMTPLZ-1
Signed-off-by: Rakesh Pillai <pillair@codeaurora.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1593194502-13164-2-git-send-email-pillair@codeaurora.org

Documentation/devicetree/bindings/net/wireless/qcom,ath10k.txt

@@ -65,7 +65,8 @@ Optional properties:
 				     the length can vary between hw versions.
 - <supply-name>-supply: handle to the regulator device tree node
 			   optional "supply-name" are "vdd-0.8-cx-mx",
-			   "vdd-1.8-xo", "vdd-1.3-rfa" and "vdd-3.3-ch0".
+			   "vdd-1.8-xo", "vdd-1.3-rfa", "vdd-3.3-ch0",
+			   and "vdd-3.3-ch1".
 - memory-region:
 	Usage: optional
 	Value type: <phandle>
@@ -204,6 +205,7 @@ wifi@18000000 {
 		vdd-1.8-xo-supply = <&vreg_l7a_1p8>;
 		vdd-1.3-rfa-supply = <&vreg_l17a_1p3>;
 		vdd-3.3-ch0-supply = <&vreg_l25a_3p3>;
+		vdd-3.3-ch1-supply = <&vreg_l26a_3p3>;
 		memory-region = <&wifi_msa_mem>;
 		iommus = <&apps_smmu 0x0040 0x1>;
 		qcom,msa-fixed-perm;