ixgbe: Acquire PHY semaphore before device reset

A recent firmware change fixed an issue to acquire the PHY semaphore before
accessing PHY registers. This led to a case where  SW can issue a device
reset clearing the MDIO registers. This patch makes SW acquire the PHY
semaphore before issuing a device reset.

Signed-off-by: Paul Greenwalt <paul.greenwalt@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>