V4L/DVB (12437): dvb: siano uses/depends on INPUT

siano uses input_*() functions so it should depend on INPUT
to prevent build errors:

ERROR: "input_event" [drivers/media/dvb/siano/sms1xxx.ko] undefined!
ERROR: "input_register_device" [drivers/media/dvb/siano/sms1xxx.ko] undefined!
ERROR: "input_free_device" [drivers/media/dvb/siano/sms1xxx.ko] undefined!
ERROR: "input_unregister_device" [drivers/media/dvb/siano/sms1xxx.ko] undefined!
ERROR: "input_allocate_device" [drivers/media/dvb/siano/sms1xxx.ko] undefined!

Cc: Michael Krufky <mkrufky@linuxtv.org>
Cc: Uri Shkolnik <uris@siano-ms.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Douglas Schilling Landgraf <dougsland@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>