net: phy: dp83867: Use unsigned variables to store unsigned properties

The variables used to store u32 DT properties were signed ints.  This
doesn't work properly if the value of the property were to overflow.
Use unsigned variables so this doesn't happen.

Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: NTrent Piepho <tpiepho@impinj.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/phy/dp83867.c

@@ -93,9 +93,9 @@ enum {
 };
 
 struct dp83867_private {
-	int rx_id_delay;
-	int tx_id_delay;
-	int fifo_depth;
+	u32 rx_id_delay;
+	u32 tx_id_delay;
+	u32 fifo_depth;
 	int io_impedance;
 	int port_mirroring;
 	bool rxctrl_strap_quirk;