Update poky to the yocto-3.1.8 revision, and also uprev the
meta-openembedded and meta-security layers to pick up latest dunfell
fixes. No BSP layers have been updated.
Bug-AGL: SPEC-3984
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Change-Id: I83c0260ca7a24f9e8594780e1248f52ad3a8e462