dcdbas: add DMI-based module autloading

DMI autoload dcdbas on all Dell systems.

This looks for BIOS Vendor or System Vendor == Dell, so this should
work for systems both Dell-branded and those Dell builds but brands
for others.  It causes udev to load the dcdbas module at startup,
which is used by tools called by HAL for wireless control and
backlight control, among other uses.

Thanks to Kay Sievers for figuring out how to do this with a single alias.

Signed-off-by: Matt Domsch <Matt_Domsch@dell.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>