Upgrade nss from 3.30.2 to latest stable version 3.31.1.
* remove 0001-Fix-warnings-found-with-gcc7.patch which is not needed now
(From OE-Core rev: 86838f1c06002a62ded12a9a66d1eb82093c85a9)
Signed-off-by: Kai Kang <kai.kang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>