MAINTAINERS: Use my infradead account exclusively for PDx86 work

ACPI PMIC subsystem listed me as a designated reviewer with
infradead email which is not what I want.

I'm using infradead email only for PDx86 related work. Thus, update
MAINTAINERS accordingly.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>