net/atm: Convert printk to pr_<level>

Add #define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__
Remove function names from output
Use single line pr_debug instead of broken multiple uses without newline

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>