Input: elantech - fix debug dump of the current packet

The use of mixed psmouse_printk() and printk creates 2 lines in the log,
while the use of %*ph solves everything.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>