crypto: qat - stop using iommu_present()

Even if an IOMMU might be present for some PCI segment in the system,
that doesn't necessarily mean it provides translation for the device
we care about. Replace iommu_present() with a more appropriate check.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>