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

This inhibits build warnings when this file doesn't exist

Change-Id: I9e51d3f23bb9988000780d8469853c6e5d1d85a7
Test: make
diff --git a/CleanSpec.mk b/CleanSpec.mk
index 0a5be5f..0c74679 100644
--- a/CleanSpec.mk
+++ b/CleanSpec.mk
@@ -61,5 +61,5 @@
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/system/build.prop)
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/obj/ETC/system_build_prop_intermediates/build.prop)
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/system/build.prop)
-$(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)