CellInfo Parceling for Invalid Values

Within CellInfo Fields, Integer.MAX_VALUE should indicate
that a field is not present in a report. This change makes the
invalid value consistent, and also ensures that it is checked
in the calculation of power levels / asu.

-Update parcel/unparcel functions to avoid -MAX_VALUE
-Update LTE and CDMA asuLevel() and level() functions to be
 consistently aware of the possibility of incomplete information

Bug: 27946114
Change-Id: Iacdc85db894e4a7809da8b5dc759488a1b6321ea