[FS#1322] DSA driver doesn't work as expected in 4.14. Fails to register mdio switches

[LEDE Bugs]

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FS#1322 - DSA driver doesn't work as expected in 4.14. Fails to register mdio switches
User who did this - Vivek (npcomplete)

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To add more information.

This is a bcm53xx device and there are two switches. The device tree looks like this.
DSA driver was working fine in 4.9 it is broken in 4.14 (or at  least below tree doesn't work)

&srab {
    compatible = "brcm,bcm53012-srab", "brcm,bcm5301x-srab";
    status = "okay";
    dsa,member = ;

    ports {
        #address-cells = ;
        #size-cells = ;

        port at 1 {
            reg = ;
            label = "lan7";
        };

        port at 2 {
            reg = ;
            label = "lan4";
        };

        port at 3 {
            reg = ;
            label = "lan8";
        };

        port at 4 {
            reg = ;
            label = "wan";
        };

        port at 8 {        
            reg = ;
            ethernet = ;    
            label = "cpu";

            fixed-link {
                speed = ;
                full-duplex;
            };
        };

        sw0port0: port at 0 {
            reg = ;    
            label = "extswitch";
            ethernet = ;

            fixed-link {
                speed = ;
                full-duplex;
            };
        };
    };  
};

&mdio {
        switch at 0  {
            compatible = "brcm,bcm53125";
            #address-cells = ;
            #size-cells = ;
            reset-gpios = ;
            reset-names = "robo_reset";
            reg = ;
            dsa,member = ;
        
            ports {
                #address-cells = ;
                #size-cells = ;
        
                port at 0 {
                        reg = ;
                        label = "lan1";
                };
        
                port at 1 {
                        reg = ;
                        label = "lan5";
                };
        
                port at 2 {
                        reg = ;
                        label = "lan2";
                };
        
                port at 3 {
                        reg = ;
                        label = "lan6";
                };
        
                port at 4 {
                        reg = ;
                        label = "lan3";
                };
        
                sw1port8:port at 8 {
                        reg = ;
                        ethernet = ;    
                        label = "dsa";

                         fixed-link {
                             speed = ;
                             full-duplex;
                         };
                };
            };
        };
};

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More information can be found at the following URL:
https://bugs.openwrt.org/index.php?do=details&task_id=1322#comment4341