net: phy: Broadcom Cygnus internal Etherent PHY driver

Add support for the Broadcom Cygnus SoCs internal PHY's.
The PHYs are 1000M/100M/10M capable with support for 'EEE'
and 'APD' (Auto Power Down).

This driver supports the following Broadcom Cygnus SoCs:
 - BCM583XX (BCM58300, BCM58302, BCM58303, BCM58305)
 - BCM113XX (BCM11300, BCM11320, BCM11350, BCM11360)

The PHY's on these SoC's require some workarounds for
stable operation, both during configuration time and
during suspend/resume. This driver handles the
application of the workarounds.

Signed-off-by: Arun Parameswaran <arunp@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>