iommu/amd: Enable GT mode when supported by IOMMU

This feature needs to be enabled before IOMMUv2 DTEs can be
set up.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
index 4dc2309..a6e1dc6 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -129,6 +129,7 @@
 #define CONTROL_PPFLOG_EN       0x0dULL
 #define CONTROL_PPFINT_EN       0x0eULL
 #define CONTROL_PPR_EN          0x0fULL
+#define CONTROL_GT_EN           0x10ULL
 
 /* command specific defines */
 #define CMD_COMPL_WAIT          0x01