dma-debug: use pr_* instead of printk(KERN_* ...)

The pr_* macros are shorter than the old printk(KERN_ ...) variant.
Change the dma-debug code to use the new macros and save a few
unnecessary line breaks. If lines don't break the source code can also
be grepped more easily.

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