raw/ioat: rename functions to be operation-agnostic

raw/ioat: rename functions to be operation-agnostic

Since the hardware supported by the ioat driver is capable of operations
other than just copies, we can rename the doorbell and completion-return
functions to not have "copies" in their names. These functions are not
copy-specific, and so would apply for other operations which may be added
later to the driver.

Also add a suitable warning using deprecation attribute for any code using
the old functions names.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Reviewed-by: Kevin Laatz <kevin.laatz@intel.com>
Acked-by: Radu Nicolau <radu.nicolau@intel.com>