i40e: Remove zero check

A mirror rule ID may be zero so do not return invalid parameter when the
user passes in a zero value for a rule ID.

Change-ID: I261b8c24725ce2c6ed32f859da81093dfcbe2970
Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>