Hammerhead cleanup
It isn't very useful to launch weston demo's on every possible installed DE, even when the weston demo's aren't installed.
The weston demo's still work after this change
This also changes the kernel cmdline to use ttyMSM0 instead of ttyHSL0 since ttyHSL0 is from the downstream kernel.
[x] Merge on GitHub (see https://postmarketos.org/merge)