e1000e: provide family-specific PHY power up/down operations

The different families (80003es2lan, 8257x, ICHx/PCH) supported by the
driver each have their own conditions when the PHY can be powered down.
This patch rewrites the PHY power up/down code to fit with the family-
specific style used in the driver.  All pre-existing calls to power up or
down the PHY remain untouched.  A new call to power down the PHY when
removing the driver when the interface is down replaces the current call
to reset the PHY in order to reduce power consumption.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>