ibmvnic: Harden device Command Response Queue handshake

In some cases, the device or firmware may be busy when the
driver attempts to perform the CRQ initialization handshake.
If the partner is busy, the hypervisor will return the H_CLOSED
return code. The aim of this patch is that, if the device is not
ready, to query the device a number of times, with a small wait
time in between queries. If all initialization requests fail,
the driver will remain in a dormant state, awaiting a signal
from the device that it is ready for operation.

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