Integrate meta-seconorth-distro/sshdgenkeys-fix

Commit: seco-ne/yocto/layers/meta-seconorth-distro@2c6b23fd

ssh: sshdgenkeys: wait for config partition

Since we have the sshd keys on a separate read-only partition that is mounted in /etc/shared at boot time, we need to wait until it is available. Otherwise, the sshdgenkeys service will not find any existing keys and will waste time trying to create the new ones. This will slow down the boot process a bit.

Add /etc/shared to RequiresMountsFor in sshdgenkeys.service