e1000e: Add handshake with the CSME to support S0ix

On the corporate system, the driver will ask from the CSME
(manageability engine) to perform device settings are required
to allow S0ix residency.
This patch provides initial support.
Reviewed-by: Dima Ruinskiy <dima.ruinskiy@intel.com>
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Dvora Fuxbrumer <dvorax.fuxbrumer@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/e1000e/ich8lan.h

@@ -47,6 +47,8 @@
 #define E1000_SHRAH_PCH_LPT(_i)		(0x0540C + ((_i) * 8))
 
 #define E1000_H2ME		0x05B50	/* Host to ME */
+#define E1000_H2ME_START_DPG	0x00000001	/* indicate the ME of DPG */
+#define E1000_H2ME_EXIT_DPG	0x00000002	/* indicate the ME exit DPG */
 #define E1000_H2ME_ULP		0x00000800	/* ULP Indication Bit */
 #define E1000_H2ME_ENFORCE_SETTINGS	0x00001000	/* Enforce Settings */