HID: hid-wiimote: print small buffers via %*phC

Instead of passing each byte through stack let's use %*phC specifier to dump
buffer as a hex string.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>