fm10k: start service timer on probe

Since the service task handles varying work that doesn't all require the
interface to be up, launch the service timer immediately. This ensures
that we continually check the mailbox, as well as handle other tasks
while the device is down.

Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Acked-by: Matthew Vick <matthew.vick@intel.com>
Tested-by: Krishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>