linux: config: enable kernel settings that systemd requires

Add kernel config fragment with all settings required by systemd.

Some more generic settings need to be explicitly set here as well to satisfy
necessary dependencies from systemd settings down the tree, otherwise some
BSPs would break.

Bug-AGL: SPEC-4627
Change-Id: I7a2796ea65da58a4f1fa0556cd94df67e7df7db9
Signed-off-by: Denys Dmytriyenko <denys@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/28275
Tested-by: Jenkins Job builder account
ci-image-build: Jenkins Job builder account
ci-image-boot-test: Jenkins Job builder account
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>