hal: Avoid stereo device selection for target with single speaker

Stereo flag is true by default, speaker device in selection
of VOICE_SPEAKER_2 during call for target with single speaker.
Fix this by set stereo flag to false for target with single
speaker to ensure proper speaker device is selected.

Change-Id: I4733270abbbce1fba976e191abef84e0710bdfca
diff --git a/hal/msm8974/hw_info.c b/hal/msm8974/hw_info.c
index 96040df..0c95d40 100755
--- a/hal/msm8974/hw_info.c
+++ b/hal/msm8974/hw_info.c
@@ -390,6 +390,8 @@
         hw_info->num_snd_devices = ARRAY_SIZE(tavil_qrd_variant_devices);
         hw_info->is_stereo_spkr = false;
         strlcpy(hw_info->dev_extn, "-hdk", sizeof(hw_info->dev_extn));
+    } else if (!strcmp(snd_card_name, "sdm845-qvr-tavil-snd-card")) {
+        hw_info->is_stereo_spkr = false;
     } else {
         ALOGW("%s: Not a sdm845 device", __func__);
     }