net: mvpp2: Cannot test unsigned variable to be negative

In phy_info_parse all uses of the variable phyaddr are as an int so
declaring as u32 is not useful and prevents the test for an error return
from fdtdec_get_int ever detecting an error. Change phyaddr to be an
int.

This issue was found by Smatch.

Signed-off-by: Andrew Goodbody <andrew.goodbody@linaro.org>

drivers/net/mvpp2.c

@@ -4734,7 +4734,7 @@ static int phy_info_parse(struct udevice *dev, struct mvpp2_port *port)
 	int port_node = dev_of_offset(dev);
 	int phy_node;
 	u32 id;
-	u32 phyaddr = 0;
+	int phyaddr = 0;
 	int fixed_link = 0;
 	int ret;