Remove dependency of 'dist_clean' on 'kvmunittests_clean'

Kvm-unit-tests are now built out-of-tree. Deleting the out/ folder
cleans it too.

Change-Id: Idc1abcf98171072c0c871f066a38b995292d6e9e
diff --git a/Makefile b/Makefile
index d5cc3e8..d66164b 100644
--- a/Makefile
+++ b/Makefile
@@ -54,7 +54,7 @@
 clean: buildroot_clean kvmunittests_clean linux_clean
 
 .PHONY: distclean
-distclean: kvmunittests_clean
+distclean:
 	- rm -rf $(OUT_DIR)
 
 .PHONY: all