fix test for remaining DBG1 macro

The test for remaining DBG1 macros (added in
 d7b9e9ab) incorrectly exited with
non-zero status and caused the cleanup.sh script to abort.

cleanup/cleanup.sh

@@ -59,7 +59,7 @@ sed -i 's|\(.*g_ftrace.*\)||g' *.{c,h}
 # remove unused DBG1 macro
 sed -i 's|\(#define DBG1.*\)||g' tn40.h
 # confirm that it really is unsused and gone
-! grep -Iq DBG1 *.{c,h} || echo 'unexpected DBG1 macro remaining.' && false
+(! grep -Iq DBG1 *.{c,h}) || (echo 'unexpected DBG1 macro remaining.' && false)
 
 
 # Insert new cleanup steps above this comment.