ice: Change req_speeds to be u16

Since the req_speeds field in struct ice_link_status is a u8,
req_speeds & ICE_AQ_LINK_SPEED_40GB always returns 0. This was caught
by a coverity scan.

Fix this by changing req_speeds to be u16.

Reported-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Chinh T Cao <chinh.t.cao@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>