ibmvnic: Fix endian error when requesting device capabilities

When a vNIC client driver requests a faulty device setting, the
server returns an acceptable value for the client to request.
This 64 bit value was incorrectly being swapped as a 32 bit value,
resulting in loss of data. This patch corrects that by using
the 64 bit swap function.

Signed-off-by: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>