sanitycheck: additional scripting hook after flashing

Support custom hooks after flashing is completed.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>
diff --git a/scripts/sanitycheck b/scripts/sanitycheck
index 832f97e..0544d96 100755
--- a/scripts/sanitycheck
+++ b/scripts/sanitycheck
@@ -777,6 +777,7 @@
         start_time = time.time()
 
         pre_script = hardware.get('pre_script')
+        post_flash_script = hardware.get('post_flash_script')
         post_script = hardware.get('post_script')
 
         if pre_script:
@@ -810,6 +811,10 @@
         except subprocess.CalledProcessError:
             os.write(write_pipe, b'x')  # halt the thread
 
+        if post_flash_script:
+            self.run_custom_script(post_flash_script, 30)
+
+
         t.join(self.timeout)
         if t.is_alive():
             logger.debug("Timed out while monitoring serial output on {}".format(self.instance.platform.name))