intel-iommu: Redefine macros to enable supporting 48 bit address width
    
    The current implementation of Intel IOMMU code only supports 39 bits
    host/iova address width so number of macros use hard coded values based
    on that. This patch is to redefine them so they can be used with
    variable address widths. This patch doesn't add any new functionality
    but enables adding support for 48 bit address width.
    
    Signed-off-by: Prasad Singamsetty <prasad.singamsety@oracle.com>
    Reviewed-by: Peter Xu <peterx@redhat.com>
    Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
    Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
    (cherry picked from commit 92e5d85e8345a22e87eda940ffe0f6422eb45360)
    Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>