UsbMidiDeviceJNI: fix race condition

Try multiple times to open the MIDI control device.
This fixes a race condition that caused Android to
sometimes not see a USB MIDI keyboard when it was plugged in.

Bug: 25328161
Change-Id: Ic72c5859364fc56bf7a40c1b1c9791c42827ea63
Signed-off-by: Phil Burk <philburk@google.com>