If the system runs out of SW-IOMMU space, changes are high successive
requests will fail, too, flooding the kernel log. This is true[...]
especially for streaming DMA, which is typically used repeatedly outside
the driver's initialization routine. Add rate-limiting to fix this.
While at it, get rid of the open-coded dev_name() handling by using the
appropriate dev_err_*() variant.
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>