The VF mailbox polling for acks and messages would reset the timer to zero
on a timeout. Under heavy load a timeout may actually occur without being
the result of an error and when this occurs it is not practical to perform
a full VF driver reset on every message timeout. Instead, just return an
error (which is already done) and the VF driver will have an opportunity
to retry the operation.

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Acked-by: Greg Rose <gregory.v.rose@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>