classes/image: improve debug-tweaks ssh server configuration
Create a single postprocessing function that enables no-password logins
for both openssh and dropbear when debug-tweaks is in IMAGE_FEATURES,
changing its behaviour slightly:
* Run it regardless of whether ssh-server-* are in IMAGE_FEATURES so
that it still takes effect if these are installed by adding
dropbear/openssh to IMAGE_INSTALL.
* Enable it to be run from image.bbclass rather than core-image.bbclass
so that it works for images that are using the former.
Second half of the fix for [YOCTO #2578].
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Saul Wold <sgw@linux.intel.com>
