rng-tools: 6.6 -> 6.7

rng-tools: 6.6 -> 6.7

Upgrade rng-tools from 6.6 to latest commit 9fc873c which 26 commits
beyond release 6.7:

$ git describe 9fc873c5af0e39263
v6.7-26-g9fc873c

Because it includes some critical fixes such as configure fails and
'Import yocto fixes for 6.6'.

* remove local patches that all are merged by upstream
* backport patch to fix rngd fails to stop issue
* add PACKAGECONFIG libp11

Signed-off-by: Kai Kang <kai.kang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>