staging: comedi: split CONFIG_COMEDI_NI_TIO option

Selecting the CONFIG_COMEDI_NI_TIO config option causes the 'ni_tio' and
'ni_tiocmd' modules to be built. CONFIG_COMEDI_NI_TIO depends on
CONFIG_COMEDI_MITE which in turn depends on CONFIG_PCI.  However, not
all the drivers that need the 'ni_tio' module also need the 'ni_tiocmd'
module.  Specifically, the ISA and PCMCIA drivers do not need the
'ni_tiocmd' module.

Add a new config option CONFIG_COMEDI_NI_TIOCMD to control building of
the 'ni_tiocmd' module.  It depends on CONFIG_COMEDI_NI_TIO and
CONFIG_COMEDI_MITE.  The existing CONFIG_COMEDI_NI_TIO option no longer
needs to depend on CONFIG_COMEDI_MITE.

Make CONFIG_COMEDI_NI_660X ('ni_660x' module) and
CONFIG_COMEDI_NI_PCIMIO ('ni_pcimio' module) depend on
CONFIG_COMEDI_NI_TIOCMD instead of CONFIG_COMEDI_NI_TIO.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>