Input: elan_i2c - fix wrong %p extension

There's no %px extension. From the context I think the intention was to
dump the five bytes which were not as expected, and for that one should use
%ph.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>