[PATCH] libata: kill E.D.D.

E.D.D. has no user in-tree and mostly useless.  Kill it.  For possible
out-of-tree users, add a nice warning message and error handling if
LLDD doesn't report any useable reset mechanism (and thus tries to use
E.D.D.).

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>