weston-init: Let weston run without pam on distros without pam
When pam is not part of distro, user specific XDG_* environment
variables are not available since PAMName=login is in-effective and as a
result weston can not start because it direly needs XDG_RUNTIME_DIR
defined, therefore launching weston directly in systemd service will not
work, therefore call the helper script weston-start, which is also used
with sysvinit
extend enabling fbdev backend fallback to all qemu machines
Reported-by: Marek Vasut <marex@denx.de> Signed-off-by: Khem Raj <raj.khem@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
