staging: comedi: Kconfig: remove VIRT_TO_BUS depends on

The only addi-data driver that uses virt_to_bus is addi_apci_3120.
Remove the depends on for the other addi-data drivers.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>