iommu/amd: Move informational prinks out of iommu_enable

This function will be called before the PCI subsystem is
initialized. Therefore dev_name doen't work and IOMMU
information can't be printed to the klog as before. Move the
code to print that information to a later point where PCI
initializtion has already happened.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>