ibmvnic: remove unused defines

IBMVNIC_STATS_TIMEOUT and IBMVNIC_INIT_FAILED are not used in the driver.
Remove them.

Suggested-by: Sukadev Bhattiprolu <sukadev@linux.ibm.com>
Signed-off-by: Dany Madden <drt@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>