Expose some data about the configuration and operation of the CCP
through debugfs entries: device name, capabilities, configuration,
statistics.

Allow the user to reset the counters to zero by writing (any value)
to the 'stats' file. This can be done per queue or per device.

Changes from V1:
 - Correct polarity of test when destroying devices at module unload
Signed-off-by: Gary R Hook <gary.hook@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>