Input: fix typo in keycode validation supporting large scancodes

Check the input_keymap_entry keycode size (u32) instead of the device's
(void*) when validating that keycode value can be stored in the keymap.

Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=22722



Signed-off-by: Mattia Dongili <malattia@linux.it>
Tested-by: Norbert Preining <preining@logic.at>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>