arm64: dts: mediatek: mt6331: Fix pmic, regulators, rtc, keys node names

arm64: dts: mediatek: mt6331: Fix pmic, regulators, rtc, keys node names

The node names for "pmic", "regulators", "rtc", and "keys" are
dictated by the PMIC MFD binding: change those to adhere to it.

Fixes: aef783f3e0ca ("arm64: dts: mediatek: Add MT6331 PMIC devicetree")
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Fei Shao <fshao@chromium.org>
Link: https://lore.kernel.org/r/20250724083914.61351-17-angelogioacchino.delregno@collabora.com
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>