Merge branch 'net-dsa-Add-Vitesse-VSC73xx-parallel-mode'

Pawel Dembicki says:

====================
net: dsa: Add Vitesse VSC73xx parallel mode

Main goal of this patch series is to add support for CPU attached parallel
bus in Vitesse VSC73xx switches. Existing driver supports only SPI mode.

Second change is needed for devices in unmanaged state.

V3:
- fix commit messages and descriptions about memory-mapped I/O mode

V2:
- drop changes in compatible strings
- make changes less invasive
- drop mutex in platform part and move mutex from core to spi part
- fix indentation
- fix devm_ioremap_resource result check
- add cover letter
====================

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