CleanSpec: add "-f" flag for broadcastradio@1.0-impl.so

This inhibits build warnings when this file doesn't exist

Change-Id: I2d65feb81c109201f9e0f195d2dfac3e8a906997
Test: make
diff --git a/CleanSpec.mk b/CleanSpec.mk
index 83059d2..c9e5cf0 100644
--- a/CleanSpec.mk
+++ b/CleanSpec.mk
@@ -49,5 +49,5 @@
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/system/etc/permissions/android.hardware.location.gps.xml)
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/system/etc/permissions/android.hardware.camera.full.xml)
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/system/etc/permissions/android.hardware.camera.manual_sensor.xml)
-$(call add-clean-step, rm $(PRODUCT_OUT)/system/lib/hw/android.hardware.broadcastradio@1.0-impl.so)
-$(call add-clean-step, rm $(PRODUCT_OUT)/system/lib64/hw/android.hardware.broadcastradio@1.0-impl.so)
+$(call add-clean-step, rm -f $(PRODUCT_OUT)/system/lib/hw/android.hardware.broadcastradio@1.0-impl.so)
+$(call add-clean-step, rm -f $(PRODUCT_OUT)/system/lib64/hw/android.hardware.broadcastradio@1.0-impl.so)