res_parking: Set load_pri more appropriately.

res_parking had an inplicit load_pri of 0 meaning it was one of the very
first modules loaded after modules with global symbols.  Set it to
AST_MODPRI_DEVSTATE_PROVIDER as it provides device state for parking
lots.

Change-Id: I297b6fb3ff6993ec004e667b22a74f5925906259