dt-bindings: net: stmmac: remove syscfg clock property

Syscfg clock is no more needed.
Signed-off-by: Christophe Roullier <christophe.roullier@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/stm32-dwmac.txt

@@ -14,8 +14,7 @@ Required properties:
 - clock-names: Should be "stmmaceth" for the host clock.
 	       Should be "mac-clk-tx" for the MAC TX clock.
 	       Should be "mac-clk-rx" for the MAC RX clock.
-	       For MPU family need to add also "ethstp" for power mode clock and,
-	                                       "syscfg-clk" for SYSCFG clock.
+	       For MPU family need to add also "ethstp" for power mode clock
 - interrupt-names: Should contain a list of interrupt names corresponding to
            the interrupts in the interrupts property, if available.
 		   Should be "macirq" for the main MAC IRQ