fix hardcoded reference to /mnt/test in common.attr

When trying to run test 70, we encountered several problems.
Sergey has strace'd some of the problems to attempts to
set xattr on the wrong test dir (/mnt/test/), which appears to be
hardcoded in common.attr.

Reported-by: Sergey Ivanov <sergey57@gmail.com>
Signed-off-by: Amir Goldstein <amir73il@users.sf.net>
Signed-off-by: Christoph Hellwig <hch@lst.de>

common.attr

@@ -163,7 +163,7 @@ _require_attrs()
     # stored on disk.
     #
     touch $TEST_DIR/syscalltest
-    attr -s "user.xfstests" -V "attr" /mnt/test/ > $TEST_DIR/syscalltest.out 2>&1
+    attr -s "user.xfstests" -V "attr" $TEST_DIR > $TEST_DIR/syscalltest.out 2>&1
     cat $TEST_DIR/syscalltest.out >> $here/$seq.full
 
     if grep -q 'Function not implemented' $TEST_DIR/syscalltest.out; then