msm: eva: Avoid nested mutext lock in dsp

Unlock dsp mutex early, right after critical section ends.
In this way, HFI queue send will lock mutex without nested
locking concern.

Change-Id: I1af64565440585e3fffe041d39d2e4a03f846c1a
Signed-off-by: George Shen <sqiao@codeaurora.org>

msm/eva/msm_cvp_dsp.c

@@ -170,8 +170,8 @@ static int cvp_dsp_rpmsg_probe(struct rpmsg_device *rpdev)
 	mutex_lock(&me->tx_lock);
 	me->chan = rpdev;
 	me->state = DSP_PROBED;
-	complete(&me->completions[CPU2DSP_MAX_CMD]);
 	mutex_unlock(&me->tx_lock);
+	complete(&me->completions[CPU2DSP_MAX_CMD]);
 
 	return ret;
 }