arm64: dts: mediatek: mt8188: Add GPU speed bin NVMEM cells

On the MT8188, 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: Hsin-Te Yuan <yuanhsinte@chromium.org>
Link: https://lore.kernel.org/r/20241213-speedbin-v1-1-a0053ead9477@chromium.org


Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>