V4L/DVB (13851): Fix Input dependency for Mantis

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> CONFIG_INPUT=n

As reported by Randy Dunlap <randy.dunlap@oracle.com>:
> ERROR: "ir_input_register" [drivers/media/dvb/mantis/mantis_core.ko] undefined!
> ERROR: "ir_input_unregister" [drivers/media/dvb/mantis/mantis_core.ko] undefined!
> ERROR: "ir_input_init" [drivers/media/dvb/mantis/mantis_core.ko] undefined!
> ERROR: "input_free_device" [drivers/media/dvb/mantis/mantis_core.ko] undefined!
> ERROR: "input_allocate_device" [drivers/media/dvb/mantis/mantis_core.ko] undefined!

Signed-off-by: Manu Abraham <manu@linuxtv.org>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>