[AGPGART] prevent probe collision of sis-agp and amd64_agp

For some vendor/id pairs the kernel will autoload both the sis-agp and the
amd64_agp modules as the sis-agp module will load for all sis devices.
This collision causes the bug reported in:
http://bugzilla.novell.com/show_bug.cgi?id=248665



As currently sis_probe does its own matching, requesting the whole range
gains nothing.  The clean fix seems to me to leave the matching to the core
and advertise only the devices actually supported.  This patch does so.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Jones <davej@redhat.com>