ixgbe: fix X540 to use it's own info struct

This patch enables X540 hardware to use it's own set of support
functions.  This is useful as it has no need of SFP+ support.  A
couple minor bugs with the eeprom semaphore were also cleaned up.

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>