Makefile: revert CCM_COMMIT_ID to master

The relevant issue: scylladb/scylla-ccm#646
has been fixed some time ago.

Author: wprzytula

Makefile

@@ -121,8 +121,7 @@ CASSANDRA_NO_VALGRIND_TEST_FILTER := $(subst ${SPACE},${EMPTY},AsyncTests.Integr
 endif
 
 ifndef CCM_COMMIT_ID
-	# TODO: change it back to master/next when https://github.com/scylladb/scylla-ccm/issues/646 is fixed.
-	export CCM_COMMIT_ID := 5392dd68
+	export CCM_COMMIT_ID := master
 endif
 
 ifndef SCYLLA_VERSION