Added hashcode for ApnSetting class

Without hashCode, ApnSetting can't be used as a key in the
map.

Fix: 162663245
Test: Manual
Merged-In: I9445ec854709996c80830e4c8c498e664f1e4f9c
Change-Id: I9445ec854709996c80830e4c8c498e664f1e4f9c
(cherry picked from commit fe59b726)