Input: allocate keycode for "Selective Screenshot" key

New Chrome OS keyboards have a "snip" key that is basically a selective
screenshot (allows a user to select an area of screen to be copied).
Allocate a keycode for it.

Signed-off-by: Rajat Jain <rajatja@google.com>
Reviewed-by: Harry Cutts <hcutts@chromium.org>
Link: https://lore.kernel.org/r/20200313180333.75011-1-rajatja@google.com


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>