net: dsa: mv88e6xxx: fix SMI bit checking

The current mv88e6xxx_smi_direct_wait function is only used to check
the 16th bit of the (16-bit) SMI Command register. But the bit shift
operation is not enough if we eventually use this function to check
other bits, thus replace it with a mask.

Fixes: e7ba0fad ("net: dsa: mv88e6xxx: refine SMI support")
Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/smi.c

@@ -64,7 +64,7 @@ static int mv88e6xxx_smi_direct_wait(struct mv88e6xxx_chip *chip,
 		if (err)
 			return err;
 
-		if (!!(data >> bit) == !!val)
+		if (!!(data & BIT(bit)) == !!val)
 			return 0;
 	}