iommu/vt-d: Correctly disable Intel IOMMU force on

I made a mistake in commit bfd20f1. We should skip the force on with the
option enabled instead of vice versa. Not sure why this passed our
performance test, sorry.

Fixes: bfd20f1 ('x86, iommu/vt-d: Add an option to disable Intel IOMMU force on')
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

arch/x86/kernel/tboot.c

@@ -514,7 +514,7 @@ int tboot_force_iommu(void)
 	if (!tboot_enabled())
 		return 0;
 
-	if (!intel_iommu_tboot_noforce)
+	if (intel_iommu_tboot_noforce)
 		return 1;
 
 	if (no_iommu || swiotlb || dmar_disabled)