The old rm (e.g., Ubuntu 12.04's) doesn't has -d option, use rmdir to
make it work. BTW., the "-f" option in rm -df doesn't make any sense.
(From OE-Core rev: 0a78e2051e6e735e3a47a8d46d150f5e62ba505c)
Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>