Use stream operator to report result code

The cast operator for KeyStoreNativeReturnCode and
KeyStoreNativeReturnCode will be removed later.
There already exists a stream operator to get
at the underlying value. Use that instead.

Bug: 119771891
Test: Built for walleye successfully.
Change-Id: I784d3c54d7b2d612201f045fe2862cf2529f4e1f
1 file changed