So if for example the controller has 2 CS lines, and the cs-gpios
property looks like this:
-cs-gpios = <&gpio1 0 0> <0> <&gpio1 1 0> <&gpio1 2 0>;
+cs-gpios = <&gpio1 0 0>, <0>, <&gpio1 1 0>, <&gpio1 2 0>;
Then it should be configured so that num_chipselect = 4 with the
following mapping: