MTP: handle bad conversion from UTF-16 to UTF-8

Test: repo sync -c -j 100 && mmm -j && flash
Test: atest mtp_ffs_handle_test
Test: HWASAN_OPTIONS="handle_abort=2" ./mtp_fuzzer all_corpus/
Bug: 137780371
Change-Id: I4bd7e926c8c04913f171806b9046d31e99fd8a73
1 file changed