xfstests: fix common source file path

After the re-factor, common.* have been renamed to common/* but there
are several files still look for the old path, fix it.

Signed-off-by: Eryu Guan <eguan@redhat.com>
Reviewed-by: Rich Johnston <rjohnston@sgi.com>
Signed-off-by: Rich Johnston <rjohnston@sgi.com>

new

@@ -23,7 +23,7 @@
 
 # generic initialization
 iam=new
-. ./common.rc
+. ./common/rc
 
 trap "rm -f /tmp/$$.; exit" 0 1 2 3 15
 
@@ -121,8 +121,8 @@ _cleanup()
 }
 
 # get standard environment, filters and checks
-. ./common.rc
-. ./common.filter
+. ./common/rc
+. ./common/filter
 
 # real QA test starts here