dt-bindings: net: Fix a typo in the phy-mode list for ethernet bindings

The phy_mode "2000base-x" is actually supposed to be "1000base-x", even
though the commit title of the original patch says otherwise.

Fixes: 55601a88 ("net: phy: Add 2000base-x, 2500base-x and rxaui modes")
Signed-off-by: NMaxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/ethernet.txt

@@ -36,7 +36,7 @@ Documentation/devicetree/bindings/phy/phy-bindings.txt.
   * "smii"
   * "xgmii"
   * "trgmii"
-  * "2000base-x",
+  * "1000base-x",
   * "2500base-x",
   * "rxaui"
   * "xaui"