libmtp: fix couple of realloc failures
libmtp: fix couple of realloc failures

[src/libmtp.c:4002]: (error) Common realloc mistake: 'localtypes' nulled but not freed upon failure
[src/libmtp.c:4009]: (error) Common realloc mistake: 'localtypes' nulled but not freed upon failure

libmtp/libmtp,libmtp/libmtp,libmtp/libmtp