counter: nxp_pit: use clock control to obtain module's clock rate

Use standard clock control API to retrieve the PIT clock rate instead of
using the HAL.

Signed-off-by: Manuel Argüelles <manuel.arguelles@nxp.com>

dts/bindings/rtc/nxp,kinetis-pit.yaml

@@ -11,6 +11,9 @@ properties:
   reg:
     required: true
 
+  clocks:
+    required: true
+
   pit-channel:
     type: int
     required: true