MAINTAINERS: Add myself for Marvell 88PM886 PMIC

Add an entry to MAINTAINERS for the Marvell 88PM886 PMIC MFD, onkey and
regulator drivers.

Signed-off-by: Karel Balej <balejk@matfyz.cz>
Link: https://lore.kernel.org/r/20240531175109.15599-6-balejk@matfyz.cz


Signed-off-by: Lee Jones <lee@kernel.org>