dt-bindings: iio: hmc425a: add conditional GPIO array size constraints

ADRF5740 and HMC540S have a 4 bit parallel interface.
Update ctrl-gpios description and min/maxItems values depending on the
matched compatible to correctly reflect the hardware properties.

Fixes: 79f2ff6461e7 ("dt-bindings: iio: hmc425a: add entry for ADRF5740 Attenuator")
Fixes: 20f87a9a26be ("dt-bindings: iio: hmc425a: add entry for HMC540S")
Acked-by: Conor Dooley <[e-mail]>
Signed-off-by: Dumitru Ceclan <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

Documentation/devicetree/bindings/iio/amplifiers/adi,hmc425a.yaml

···
 
   ctrl-gpios:
     description:
-      Must contain an array of 6 GPIO specifiers, referring to the GPIO pins
-      connected to the control pins V1-V6.
-    minItems: 6
+      Must contain an array of GPIO specifiers, referring to the GPIO pins
+      connected to the control pins.
+        ADRF5740  - 4 GPIO connected to D2-D5
+        HMC540S   - 4 GPIO connected to V1-V4
+        HMC425A   - 6 GPIO connected to V1-V6
+    minItems: 1
     maxItems: 6
+
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: adi,hmc425a
+    then:
+      properties:
+        ctrl-gpios:
+          minItems: 6
+          maxItems: 6
+  - if:
+      properties:
+        compatible:
+          contains:
+            anyOf:
+              - const: adi,adrf5740
+              - const: adi,hmc540s
+    then:
+      properties:
+        ctrl-gpios:
+          minItems: 4
+          maxItems: 4
 
 required:
   - compatible