Merge branch 'dp83867-fix-fifo-depth'

Dan Murphy says:

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Fix Tx/Rx FIFO depth for DP83867

The DP83867 supports both the RGMII and SGMII modes.  The Tx and Rx FIFO depths
are configurable in these modes but may not applicable for both modes.

When the device is configured for RGMII mode the Tx FIFO depth is applicable
and for SGMII mode both Tx and Rx FIFO depth settings are applicable.  When
the driver was originally written only the RGMII device was available and there
were no standard fifo-depth DT properties.

The patchset converts the special ti,fifo-depth property to the standard
tx-fifo-depth property while still allowing the ti,fifo-depth property to be
set as to maintain backward compatibility.

In addition to this change the rx-fifo-depth property support was added and only
written when the device is configured for SGMII mode.
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Signed-off-by: David S. Miller <davem@davemloft.net>