Fix JNI for sendDtmfNative

sendDtmfNative had the parameters reversed in the static function
declaration causing DTMF (dial tones durring a call) to crash the BT
stack.

Bug: 36359320
Test: Make a phonecall via HFP and tap digits, observe no crash and
proper AT+VTS commands in btsnoop_hci.log.

Change-Id: Icf66a22886bfebd6aebcf1033f59d0562c57db2f