input: event.h: include gp_keys.h
input: event.h: include gp_keys.h

We have to include the header so that the function is defined

Fixes: ca01cf7b894895 (input/gp_event.h: Remove forgotten function declaration)
Signed-off-by: Cyril Hrubis <b1e90efd3b808b8e0bcf2a9a55fd8b9a779bfd81@ucw.cz>

gfxprim/gfxprim,gfxprim/gfxprim,gfxprim/gfxprim,gfxprim/gfxprim,gfxprim/gfxprim