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().

Bug: 130843208
Test: perfomed BT on and off use case not seen NPE.

Change-Id: Idec03ba93415ef8335093e310142933cecb2b85c