Revert "weston-init: Pass --continue-without-input when launching weston"

This reverts commit 762a20b4.

This breaks machines using fbdev backend, since this option is drm
backend specific, we need to know the backend before using it, until we
have a smart way to detect that, this will not be a fool proof solution,
therefore revert it for now.

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>