tests/drivers kscan_input: Switch to native_sim

Switch from native_posix to native_sim as default test platform
And switch overlays to native_sim.

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>

tests/drivers/kscan/kscan_input/boards/native_sim_64.overlay

@@ -3,4 +3,4 @@
  *
  * SPDX-License-Identifier: Apache-2.0
  */
-#include "native_posix.overlay"
+#include "native_sim.overlay"

tests/drivers/kscan/kscan_input/testcase.yaml

@@ -3,11 +3,11 @@
 tests:
   drivers.input.kscan_input:
     platform_allow:
-      - native_posix
-      - native_posix_64
+      - native_sim
+      - native_sim_64
     tags:
       - drivers
       - kscan
       - input
     integration_platforms:
-      - native_posix
+      - native_sim