snippets: hw-flow-control: add missing configuration for nrf54

Missing entries in yml file.

Signed-off-by: Piotr Kosycarz <[email protected]>

Author: nordic-piks

snippets/hw-flow-control/snippet.yml

@@ -10,3 +10,9 @@ boards:
   nrf5340dk/nrf5340/cpuapp:
     append:
       EXTRA_DTC_OVERLAY_FILE: boards/nrf5340dk_nrf5340_cpuapp.overlay
+  nrf54h20dk/nrf54h20/cpuapp:
+    append:
+      EXTRA_DTC_OVERLAY_FILE: boards/nrf54h20dk_nrf54h20_cpuapp.overlay
+  nrf54l15dk/nrf54l15/cpuapp:
+    append:
+      EXTRA_DTC_OVERLAY_FILE: boards/nrf54l15dk_nrf54l15_cpuapp.overlay