ice: Change message level

Change the message level of the MTU change log message from debug to
info.

Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>