Merge branch 'dsa-b53-SerDes-support'

Florian Fainelli says:

====================
net: dsa: b53: SerDes support

This patch series adds support for the SerDes found on NorthStar Plus
(NSP) which allows us to use the SFP port on the BCM958625HR board (and
other similar designs).

Changes in v3:

- properly hunk the request_threaded_irq() bits into patch #2

Changes in v2:

- migrate to threaded interrupt (Andrew)
- fixed a case where MLO_AN_FIXED's mac_config would still call into
  the serdes_config callback
- added an additional check on the phylink interface in mac_config
- default to ARCH_BCM_NSP instead of ARCH_BCM_IPROC which is really
  the NSP Kconfig bit we want
====================

Signed-off-by: David S. Miller <davem@davemloft.net>