openpic: fix debug prints

Fix various format errors when debug prints are enabled.  Also
cause error checking to happen even when debug prints are not
enabled, and consistently use 0x for hex output.

Signed-off-by: Scott Wood <scottwood@freescale.com>
[agraf: adjust for more recent code base, prettify DPRINTF macro]
Signed-off-by: Alexander Graf <agraf@suse.de>
