HID: Fix the potential NPE in HidHostService jni callback

Add mutex-based protection mechanism to the HID JNI layer to avoid a race condition
during graceful cleaning up of the Bluetooth HID Interface when Bluetooth
is disabled, and native upcalls like connection_state_callback().

CRs-Fixed: 2437643
Change-Id: Iafd9dabbed73dd93159d9f74e6adbe6a6dcb1cfe
1 file changed