arm64: dts: qcom: sc7280: On QCard, regulator L3C should be 1.8V

On the first sc7280 QCards the L3C rail was never really used for
anything. Stuffing options on the QCard meant that the QCard itself
didn't use this rail for anything. This rail did get sent to the
mainboard, but no existing mainboards ever did anything with it other
that route it to a testpoint.

On later sc7280 QCards, the L3C rail was repurposed. Instead of being
a (nominally) 3.3V rail, it was decided to make it a 1.8V rail. It is
now provided to the display connector (which might route it to the
touchscreen) and also used to power some buffers relating to
touchscreen IO. This rail is getting the additional tag "ts_avccio",
though some places still refer to it as "vreg_l3c_3p0" despite the
fact that the name now specifies the wrong voltage.

Since it never hurts for this rail to be 1.8V (even on old QCards /
old boards), let's just change it to 1.8V across the board and add the
extra "ts_avccio" moniker as a label in the device tree.

Future patches will start using this rail in their touchscreens.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230206184744.1.I784f4b3d7e4a06edafff4a3129f52e749889bc05@changeid

arch/arm64/boot/dts/qcom/sc7280-qcard.dtsi

@@ -230,9 +230,15 @@ vreg_l2c_1p8: ldo2 {
 			regulator-initial-mode = <RPMH_REGULATOR_MODE_HPM>;
 		};
 
+		/*
+		 * The initial design of this regulator was to use it as 3.3V,
+		 * but due to later changes in design it was changed to 1.8V.
+		 * The original name is kept due to same schematic.
+		 */
+		ts_avccio:
 		vreg_l3c_3p0: ldo3 {
-			regulator-min-microvolt = <2800000>;
-			regulator-max-microvolt = <3540000>;
+			regulator-min-microvolt = <1800000>;
+			regulator-max-microvolt = <1800000>;
 			regulator-initial-mode = <RPMH_REGULATOR_MODE_HPM>;
 		};