"grep" command will return 1 if nothing is grepped, which will cause
the udevd daemon not working correctly.
This fixes [YOCTO #1146]
(From OE-Core rev: 155a10287bbcac583d95325ab2a7b09e04bb4b90)
Signed-off-by: Dongxiao Xu <dongxiao.xu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>