dt-bindings: iio: imu: st_lsm6dsx: support active-low interrupts

Update st_lsm6dsx device binding with active-low interrupts support
(IRQ_TYPE_LEVEL_LOW and IRQ_TYPE_EDGE_FALLING).

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@st.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Documentation/devicetree/bindings/iio/imu/st_lsm6dsx.txt

@@ -13,7 +13,8 @@ Optional properties:
   "data ready" (valid values: 1 or 2).
 - interrupt-parent: should be the phandle for the interrupt controller
 - interrupts: interrupt mapping for IRQ. It should be configured with
-  flags IRQ_TYPE_LEVEL_HIGH or IRQ_TYPE_EDGE_RISING.
+  flags IRQ_TYPE_LEVEL_HIGH, IRQ_TYPE_EDGE_RISING, IRQ_TYPE_LEVEL_LOW or
+  IRQ_TYPE_EDGE_FALLING.
 
   Refer to interrupt-controller/interrupts.txt for generic interrupt
   client node bindings.