amd_iommu: Fix masks for various IOMMU MMIO Registers

amd_iommu: Fix masks for various IOMMU MMIO Registers

Address various issues with definitions of the MMIO registers e.g. for the
Device Table Address Register, the size mask currently encompasses reserved
bits [11:9], so change it to only extract the bits [8:0] encoding size.

Convert masks to use GENMASK64 for consistency, and make unrelated
definitions independent.

Cc: qemu-stable@nongnu.org
Fixes: d29a09ca6842 ("hw/i386: Introduce AMD IOMMU")
Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Message-Id: <20250617150427.20585-5-alejandro.j.jimenez@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit 108e10ff69099c3ebe147f505246be7c2ad2a499)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>