staging: comedi: amplc_pci230: rewrite shared resource handling

staging: comedi: amplc_pci230: rewrite shared resource handling

Some counter channels may be required for AI commands and AO commands.
Depending on how the commands are set up, it may not be possible to run
both at the same time, so we keep some state and code to find out if the
required resources are busy or not.

The existing code is a bit unwieldy - the code for claiming resources
involves two `for` loops for example.  Rewrite it to make it simpler.

The new code just has a bit-mask value for each shared resource (counter
channels), and an array indexed by resource "owners" (AI and AO
commands), so the code for claiming resources now just has a single loop
that checks that none of the other owners have claimed the wanted
resources.

Rename the functions involved, because the old names involving 'put' and
'get' suggested some sort of usage counting.

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