ixgb: convert uint16_t style integers to u16

Conglomerate of 4 separate patches by Joe.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>