Remove MIN and MAX checking for hidl_enum in UserHalHelper native library.

VehiclePropValue enums is not sorted by their values. Thus obtaining MIN and MAX values for this enum is O(N), which is the same as looping through all the values and checking whether a given int32_t is in the enum.

Test: Tested with `atest -c android.hardware.automotive.vehicle@2.0-utils-unit-tests`.
Bug: 168249409

Change-Id: I296a56e31caa7a5ee69eac49806810f83e46571e