AGP: Try unsupported AGP chipsets on x86-64 by default

So far all new ones have worked and there isn't much variation
because the CPU does all the interesting bits.

So enable try unsupported by default.

Can be still disabled with try_unsupported=0 (module) or 
amd64.try_unsupported=0   (boot option) 

Signed-off-by: Andi Kleen <ak@suse.de>

Index: linux/drivers/char/agp/amd64-agp.c
===================================================================
--- linux.orig/drivers/char/agp/amd64-agp.c
+++ linux/drivers/char/agp/amd64-agp.c
@@ -55,7 +55,7 @@ static int nr_garts;
 static struct pci_dev * hammers[MAX_HAMMER_GARTS];
 
 static struct resource *aperture_resource;
-static int __initdata agp_try_unsupported;
+static int __initdata agp_try_unsupported = 1;
 
 static int gart_iterator;
 #define for_each_nb() for(gart_iterator=0;gart_iterator<nr_garts;gart_iterator++)