arm64: dts: exynos: Align MAX77843 nodes with dtschema on TM2

The newly introduced dtschema for MAX77843 MUIC require the children to
have proper naming and a port@0 property.

This should not have actual impact on MFD children driver binding,
because the max77843 MFD driver uses compatibles.  The port@0 is
disabled to avoid any impact.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20220111174805.223732-2-krzysztof.kozlowski@canonical.com