hal: fix mutex unlock issue

If a audio/voice usecase is active, hal should re-try the speaker
calibration.Speaker portection mutex was not being unlocked for this
usecase which causes ANR.Change unlocks the mutex which fixes the issue.

CRs-fixed: 671620
Change-Id: Ic29697e29e96dba784941f4e29664b8c10f51e84
diff --git a/hal/audio_extn/spkr_protection.c b/hal/audio_extn/spkr_protection.c
index cd2a94e..b1ad358 100644
--- a/hal/audio_extn/spkr_protection.c
+++ b/hal/audio_extn/spkr_protection.c
@@ -544,8 +544,11 @@
             }
             goahead = true;
         }
-        if (!list_empty(&adev->usecase_list))
+        if (!list_empty(&adev->usecase_list)) {
+            ALOGD("%s: Usecase active re-try calibration", __func__);
             goahead = false;
+            pthread_mutex_unlock(&handle.mutex_spkr_prot);
+        }
         if (goahead) {
                 int status;
                 status = spkr_calibrate(t0);