iommu/amd: Split amd_iommu_init function

The hardware-initializtion part of the AMD IOMMU driver is
split out into a seperate function. This function can now be
called either from amd_iommu_init() itself or any other
place if the hardware needs to be ready earlier. This will
be used to implement interrupt remapping for AMD.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
diff --git a/include/linux/amd-iommu.h b/include/linux/amd-iommu.h
index ef00610..15f6b9e 100644
--- a/include/linux/amd-iommu.h
+++ b/include/linux/amd-iommu.h
@@ -28,7 +28,7 @@
 struct pci_dev;
 
 extern int amd_iommu_detect(void);
-
+extern int amd_iommu_init_hardware(void);
 
 /**
  * amd_iommu_enable_device_erratum() - Enable erratum workaround for device