ixgbe: Always turn PHY power on when requested

Instead of inhibiting PHY power control when manageability is
present, only inhibit turning PHY power off when manageability
is present. Consequently, PHY power will always be turned on when
requested. Without this patch, some systems with X540 or X550
devices in some conditions will never get link.

Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>