V4L/DVB: Fix IR_CORE dependencies

As pointed by Randy Dunlap <randy.dunlap@oracle.com>:
> ERROR: "ir_keydown" [drivers/media/video/ir-kbd-i2c.ko] undefined!
> ERROR: "__ir_input_register" [drivers/media/video/ir-kbd-i2c.ko] undefined!
> ERROR: "get_rc_map" [drivers/media/video/ir-kbd-i2c.ko] undefined!
> ERROR: "ir_input_unregister" [drivers/media/video/ir-kbd-i2c.ko] undefined!
> ERROR: "get_rc_map" [drivers/media/video/cx88/cx88xx.ko] undefined!
> ERROR: "ir_repeat" [drivers/media/video/cx88/cx88xx.ko] undefined!
> ERROR: "ir_input_unregister" [drivers/media/video/cx88/cx88xx.ko] undefined!
> ERROR: "ir_keydown" [drivers/media/video/cx88/cx88xx.ko] undefined!
> ERROR: "__ir_input_register" [drivers/media/video/cx88/cx88xx.ko] undefined!
> ERROR: "get_rc_map" [drivers/media/video/bt8xx/bttv.ko] undefined!
> ERROR: "ir_input_unregister" [drivers/media/video/bt8xx/bttv.ko] undefined!
> ERROR: "__ir_input_register" [drivers/media/video/bt8xx/bttv.ko] undefined!
> ERROR: "ir_g_keycode_from_table" [drivers/media/IR/ir-common.ko] undefined!
>
>
> #5101:
> (.text+0x8306e2): undefined reference to `ir_core_debug'
> (.text+0x830729): undefined reference to `ir_core_debug'
> ir-functions.c:(.text+0x830906): undefined reference to `ir_core_debug'
> (.text+0x8309d8): undefined reference to `ir_g_keycode_from_table'
> (.text+0x830acf): undefined reference to `ir_core_debug'
> (.text+0x830b92): undefined reference to `ir_core_debug'
> (.text+0x830bef): undefined reference to `ir_core_debug'
> (.text+0x830c6a): undefined reference to `ir_core_debug'
> (.text+0x830cf7): undefined reference to `ir_core_debug'
> budget-ci.c:(.text+0x89f5c8): undefined reference to `ir_keydown'
> budget-ci.c:(.text+0x8a0c58): undefined reference to `get_rc_map'
> budget-ci.c:(.text+0x8a0c80): undefined reference to `__ir_input_register'
> budget-ci.c:(.text+0x8a0ee0): undefined reference to `get_rc_map'
> budget-ci.c:(.text+0x8a11cd): undefined reference to `ir_input_unregister'
> (.text+0x8a8adb): undefined reference to `ir_input_unregister'
> dvb-usb-remote.c:(.text+0x8a9188): undefined reference to `get_rc_map'
> dvb-usb-remote.c:(.text+0x8a91b1): undefined reference to `__ir_input_register'
> dvb-usb-remote.c:(.text+0x8a9238): undefined reference to `get_rc_map'
> dib0700_core.c:(.text+0x8b04ca): undefined reference to `ir_keydown'
> dib0700_devices.c:(.text+0x8b2ea8): undefined reference to `ir_keydown'
> dib0700_devices.c:(.text+0x8b2ef0): undefined reference to `ir_keydown'

Those breakages seem to be caused by two bad things at IR_CORE Kconfig:

1) cx23885 is using select for IR_CORE;
2) the dvb-usb and sms dependency for IR_CORE were missing.

While here, allow users to un-select IR.

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