EPT/VT-d: disable page sharing by default.

Currently sharing these page tables causes a hang on boot on some
hardware. Disable by default until this is resolved.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>

xen/drivers/passthrough/vtd/iommu.c

@@ -45,7 +45,7 @@
 #define nr_ioapics              iosapic_get_nr_iosapics()
 #endif
 
-static int sharept = 1;
+static int sharept = 0;
 boolean_param("sharept", sharept);
 
 int nr_iommus;