Use the correct method to unparcel the property map

We were writing the map as a generic Map, but reading it as an
ArrayMap. There's a subtle difference between the two methods.
The generic Map creator reads the map's key using readValue(),
which first reads an integer datatype and then the data. Whereas
the ArrayMap creator knows the keys are Strings and thus calls
readString() directly without consuming the datatype. This
throws the parcel reading logic out of whack.

Fixes: 176295431
Test: manual
Change-Id: I2d32488e3339e2d838e680be1ed9476b9e15cd69