arm64: dts: mediatek: mt8192-asurada: Fix voltage constraint for Vgpu

arm64: dts: mediatek: mt8192-asurada: Fix voltage constraint for Vgpu

The MT8192 SoC specifies a maximum voltage for the GPU's digital supply
of 0.88V and the GPU OPPs are declaring a maximum voltage of 0.80V.

In order to keep the GPU voltage in the safe range, change the maximum
voltage for mt6315@7's vbuck1 to 0.80V as sending, for any mistake,
1.193V would be catastrophic.

Fixes: 3183cb62b033 ("arm64: dts: mediatek: asurada: Add SPMI regulators")
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Chen-yu Tsai <wenst@chromium.org>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
Link: https://lore.kernel.org/r/20230301095523.428461-12-angelogioacchino.delregno@collabora.com
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>