Add logic to implement the interface for live migration defined in
qat/qat_mig_dev.h. This is specific for QAT GEN4 Virtual Functions
(VFs).

This introduces a migration data manager which is used to handle the
device state during migration. The manager ensures that the device state
is stored in a format that can be restored in the destination node.

The VF state is organized into a hierarchical structure that includes a
preamble, a general state section, a MISC bar section and an ETR bar
section. The latter contains the state of the 4 ring pairs contained on
a VF. Here is a graphical representation of the state:

    preamble | general state section | leaf state
             | MISC bar state section| leaf state
             | ETR bar state section | bank0 state section | leaf state
                                     | bank1 state section | leaf state
                                     | bank2 state section | leaf state
                                     | bank3 state section | leaf state

In addition to the implementation of the qat_migdev_ops interface and
the state manager framework, add a mutex in pfvf to avoid pf2vf messages
during migration.
Signed-off-by: Xin Zeng <xin.zeng@intel.com>
Reviewed-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>