lxfb: disable suspend VT switch by default

By default disable VT switch, but allow it to be overridden via the
'vt_switch' module arg.

Signed-off-by: Andres Salomon <dilinger@debian.org>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: Jordan Crouse <jordan.crouse@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>