Add checkpatch.pl to presubmit tests.

Change-Id: I235ea140f5f54dc8b22f1c69dcff5e99a34ff602
diff --git a/src/api.c b/src/api.c
index 8ff3b60..7341bfc 100644
--- a/src/api.c
+++ b/src/api.c
@@ -274,7 +274,7 @@
 /**
  * Check that the mode indicates memory that is valid, owned and exclusive.
  */
-bool static api_mode_valid_owned_and_exclusive(int mode)
+static bool api_mode_valid_owned_and_exclusive(int mode)
 {
 	return (mode & (MM_MODE_INVALID | MM_MODE_UNOWNED | MM_MODE_SHARED)) ==
 	       0;