libinput: Replace usage of _get_target() with corresponding new get:er

The target union was replaced with direct get:ers used on an event to
get associated device or context.

Signed-off-by: Jonas Ådahl <jadahl@gmail.com>
libinput: Use libinput_seat_get_logical_name() to get seat name

Replaces the use of libinput_seat_get_name().

Signed-off-by: Jonas Ådahl <jadahl@gmail.com>
libinput: Update to follow new event names

Signed-off-by: Jonas Ådahl <jadahl@gmail.com>