arm64: dts: mediatek: mt8186: Fix supported-hw mask for GPU OPPs

arm64: dts: mediatek: mt8186: Fix supported-hw mask for GPU OPPs

The speedbin eFuse reads a value 'x' from 0 to 7 and, in order to
make that compatible with opp-supported-hw, it gets post processed
as BIT(x).

Change all of the 0x30 supported-hw to 0x20 to avoid getting
duplicate OPPs for speedbin 4, and also change all of the 0x8 to
0xcf because speedbins different from 4 and 5 do support 900MHz,
950MHz, 1000MHz with the higher voltage of 850mV, 900mV, 950mV
respectively.

Fixes: f38ea593ad0d ("arm64: dts: mediatek: mt8186: Wire up GPU voltage/frequency scaling")
Link: https://lore.kernel.org/r/20240725072243.173104-1-angelogioacchino.delregno@collabora.com
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>