USB: gadget: android: Integrate f_midi USB MIDI gadget driver

Change-Id: I4c4b99f9d54314fc31445cf42b825527ca483af9
Signed-off-by: Mike Lockwood <lockwood@google.com>
Git-commit: 3f048135f3028e503d9d6e32b602e362bd9f374f
Git-repo: https://android.googlesource.com/kernel/common/


[mrana@codeaurora.org: Fix minor merged conflict, compilation error]
Signed-off-by: Mayank Rana <mrana@codeaurora.org>