arm64: dts: mediatek: mt8186: Add GPU speed bin NVMEM cells

On the MT8186, the chip is binned for different GPU voltages at the
highest OPPs. The binning value is stored in the efuse.

Add the NVMEM cell, and tie it to the GPU.
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230609072906.2784594-4-wenst@chromium.orgSigned-off-by: Matthias Brugger <matthias.bgg@gmail.com>

arch/arm64/boot/dts/mediatek/mt8186.dtsi

@@ -1519,6 +1519,11 @@ efuse: efuse@11cb0000 {
 			reg = <0 0x11cb0000 0 0x1000>;
 			#address-cells = <1>;
 			#size-cells = <1>;
+
+			gpu_speedbin: gpu-speed-bin@59c {
+				reg = <0x59c 0x4>;
+				bits = <0 3>;
+			};
 		};
 
 		mipi_tx0: dsi-phy@11cc0000 {
@@ -1551,6 +1556,8 @@ gpu: gpu@13040000 {
 					<&spm MT8186_POWER_DOMAIN_MFG3>;
 			power-domain-names = "core0", "core1";
 			#cooling-cells = <2>;
+			nvmem-cells = <&gpu_speedbin>;
+			nvmem-cell-names = "speed-bin";
 			status = "disabled";
 		};