dt-bindings: iio: gyroscope: bosch,bmg160: correct number of pins

BMG160 has two interrupt pins to which interrupts can be freely mapped.
Correct the schema to express such case and fix warnings like:

qcom/msm8916-alcatel-idol347.dtb: gyroscope@68: interrupts: [[97, 1], [98, 1]] is too long

However the basic issue still persists - the interrupts should come in a
defined order.

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

Documentation/devicetree/bindings/iio/gyroscope/bosch,bmg160.yaml

···
 
   interrupts:
     minItems: 1
+    maxItems: 2
     description:
       Should be configured with type IRQ_TYPE_EDGE_RISING.
+      If two interrupts are provided, expected order is INT1 and INT2.
 
 required:
   - compatible