Fix KCM key mapping cloning

ag/23792288 tried to fix a security issue by cloning the key
mappings, but unfortunately the parcel was not being rewinded.

Bug: 274058082
Test: Confirmed change works in newer Android versions
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:aaaba6cf190d976efdc5db6c78997dbdc9214c15)
Merged-In: I6f75b9202e20d82ebf81a35a2916e653ee1b8372
Change-Id: I6f75b9202e20d82ebf81a35a2916e653ee1b8372