Remove ultrasound system properties.

Using config.xml in lieu of system properties. See b/21072209

Change-Id: I4ea4565bcd05eb5a5b0c43c8ba15ec9e8bac68ff
diff --git a/device-common.mk b/device-common.mk
index 64e9ab3..d078a05 100644
--- a/device-common.mk
+++ b/device-common.mk
@@ -283,11 +283,6 @@
 	ro.hwui.text_large_cache_width=2048 \
 	ro.hwui.text_large_cache_height=1024
 
-# Near-ultrasound support in the default audio and speaker paths.
-PRODUCT_PROPERTY_OVERRIDES += \
-    persist.audio.spkr.ultrasound=true \
-    persist.audio.mic.ultrasound=true
-
 PRODUCT_PACKAGES += \
     power.flo