PNP: add debug output to encoders

Add debug output to encoders (enabled by CONFIG_PNP_DEBUG).  This
uses dev_printk, so I had to add pnp_dev arguments at the same time.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Acked-By: Rene Herman <rene.herman@gmail.com>
Signed-off-by: Len Brown <len.brown@intel.com>