iommu: Move new probe_device path to separate function

This makes it easier to remove to old code-path when all drivers are
converted. As a side effect that it also fixes the error cleanup
path.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20200429133712.31431-11-joro@8bytes.org


Signed-off-by: Joerg Roedel <jroedel@suse.de>