drm/vmwgfx: remove CONFIG_INTEL_IOMMU ifdefs v2

intel_iommu_enabled is defined as always false for !CONFIG_INTEL_IOMMU,
so remove the ifdefs around it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>