dmaengine: idxd: Add support for device/wq defaults

Add a load_device_defaults() function pointer to struct
idxd_driver_data, which if defined, will be called when an idxd device
is probed and will allow the idxd device to be configured with default
values.

The load_device_defaults() function is passed an idxd device to work
with to set specific device attributes.

Also add a load_device_defaults() implementation IAA devices; future
patches would add default functions for other device types such as
DSA.

The way idxd device probing works, if the device configuration is
valid at that point e.g. at least one workqueue and engine is properly
configured then the device will be enabled and ready to go.

The IAA implementation, idxd_load_iaa_device_defaults(), configures a
single workqueue (wq0) for each device with the following default
values:

mode "dedicated"
threshold 0
size Total WQ Size from WQCAP
priority 10
type IDXD_WQT_KERNEL
group 0
name "iaa_crypto"
driver_name "crypto"

Note that this now adds another configuration step for any users that
want to configure their own devices/workqueus with something different
in that they'll first need to disable (in the case of IAA) wq0 and the
device itself before they can set their own attributes and re-enable,
since they've been already been auto-enabled. Note also that in order
for the new configuration to be applied to the deflate-iaa crypto
algorithm the iaa_crypto module needs to unregister the old version,
which is accomplished by removing the iaa_crypto module, and
re-registering it with the new configuration by reinserting the
iaa_crypto module.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>