Prevent crash from unknown mime type

Some devices may have codecs for mime types that are not known to us.

Test: make cts -j123 && cts-tradefed run cts-dev -m \
CtsMediaTestCases --compatibility:module-arg \
CtsMediaTestCases:include-annotation:\
android.platform.test.annotations.RequiresDevice

Bug: 65449180
Change-Id: Idc5ed5ac0e26d8bf26f576003d1370222af10c08