base: Switch to the dev branch

It tracks poky master, we want to follow development more closely as
there are more updates.
Add sddm component
Remove kmod

It's provided by the base system where we already have the kernel.
If our kernel requires a more recent kmod we have more control there.
Drop libxml2 component

Use the one from poky.
Drop libxslt component

Use the one from poky.
glib: Track 2.37.5

Follow a released version.
Drop intltool component

Use the one from poky.
Drop parted component

We use the one from poky.