ixgbe: add function pointer for semaphore function

The X540 devices grabs semaphores differently than 82599 and 82598
devices do.  They do however also grab them in allot of the same
functions.  So I'm adding a new MAC operation function pointer to
allow us to use the correct function based on our MAC type.  I'm also
changing all the semaphore calls to use this new function pointer.

Signed-off-by: Don Skidmore <donald.c.skidmore@intel.com>
Tested-by: Stephen Ko <stephen.s.ko@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>