e1000e: move force SMBUS from enable ulp function to avoid PHY loss issue

Forcing SMBUS inside the ULP enabling flow leads to sporadic PHY loss on
some systems. It is suspected to be caused by initiating PHY transactions
before the interface settles.

Separating this configuration from the ULP enabling flow and moving it to
the shutdown function allows enough time for the interface to settle and
avoids adding a delay.

Fixes: 6607c99e ("e1000e: i219 - fix to enable both ULP and EEE in Sx state")
Co-developed-by: Dima Ruinskiy <dima.ruinskiy@intel.com>
Signed-off-by: Dima Ruinskiy <dima.ruinskiy@intel.com>
Signed-off-by: Vitaly Lifshits <vitaly.lifshits@intel.com>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>