HID: i2c-hid: fix i2c_hid_dbg macro

This avoids the problematic case:

if (condition)
	i2c_hid_dbg(ihid, "Blah blah %d\n", i);
else
	do_something_very_important();

Which looks correct, however with the previous macro definition,
this expands to the unexpected:

if (condition) {
	if (debug)	\
		dev_printk(KERN_DEBUG, &ihid->client->dev,
				"Blah blah %d\n", i);
	else
		do_something_very_important();
}

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Reviewed-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>