e1000e Refactor of Runtime Power Management

Fix issues with:
RuntimePM causing the device to repeatedly flip between suspend and resume
with the interface administratively downed.
Having RuntimePM enabled interfering with the functionality of Energy
Efficient Ethernet.

Added checks to disallow functions that should not be executed if the
device is currently runtime suspended

Make runtime_idle callback to use same deterministic behavior as the igb
driver.

Signed-off-by: Dave Ertman <davidx.m.ertman@intel.com>
Acked-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>