Avoid Calendar's unexpect change in snapToCycleDay()

Symptom:
Calendar object's certain field is unexpectedly changed after
using Calendar.add() method.

Detail and sample:
Following patch causes this issue.
- Switch network cycle calculation to use Calendar.
  https://android.googlesource.com/platform/frameworks/base/+/f2bead5

Call of Calendar.add() method might make a smaller field value
invariant. The smaller field means such a field of
Calendar.HOUR_OF_DAY, Calendar.MINUTE, Calendar.SECOND and so on
if Calendar.MONTH field is focused.
According to above, sometimes correct Calendar value won't be
acquired by original code.
To avoid unexpected change, it requires initialization toward
each smaller field after Calendar.add() call.

Solutions:
Calendar.DAY_OF_MONTH, Calendar.HOUR_OF_DAY, Calendar.MINUTE,
and Calendar.SECOND fields is set to 0 after added value to
Calendar.MONTH field.

Bug: 32724903
Author: Shigeki Yokomichi <shigeki.x.yokomichi@sonymobile.com>
Change-Id: I7af6391653be21786b662b2f8eaad10c413733c1