ntb_tool: Fix printk format

The correct printk format is %pa or %pap, but not %pa[p].

Fixes: 7f46c8b3 ("NTB: ntb_tool: Add full multi-port NTB API support")
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Jon Mason <jdmason@kudzu.us>