ipw2100: remove custom debug-print macros

From: Pavel Machek <pavel@ucw.cz>

ipw2100 uses custom debug prints that are sometimes longer and always
harder to read than normal printk. They also introduced some bugs where
prefix is printed twice.
Signed-off-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Jiri Benc <jbenc@suse.cz>