Input: sparse-keymap - fix KEY_VSW handling in sparse_keymap_setup

We were forgetting to set up device capabilities for KEY_VSW entries.

Reported-by: Tapio Vihuri <tapio.vihuri@nokia.com>
Tested-by: Tapio Vihuri <tapio.vihuri@nokia.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>