Staging: dream: remove dream driver and arch from tree

This code is stalled, with no one working on it anymore, and the main
msm code is now going through the proper channels to get merged
correctly.

So remove it as it contains a number of kernel information leaks and it
is doubtful if it even still builds anymore.

Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Bryan Huntsman <bryanh@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>