Input: cros_ec_keyb - clarify key event error message

Input: cros_ec_keyb - clarify key event error message

Reword one of the key event error messages to clarify its meaning: it's
not necessarily an incomplete message, more of a mismatch length.
Clarify that and log the expected and received length too.

Signed-off-by: Fabio Baltieri <fabiobaltieri@chromium.org>
Reviewed-by: Simon Glass <simon.glass@canonical.com>
Link: https://patch.msgid.link/20251209154706.529784-2-fabiobaltieri@chromium.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>