kernel: userspace: rename z_thread_perms_clear -> k_thread_perms_clear

Rename z_thread_perms_clear -> k_thread_perms_clear.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>
diff --git a/kernel/userspace_handler.c b/kernel/userspace_handler.c
index cbec324..74ee493 100644
--- a/kernel/userspace_handler.c
+++ b/kernel/userspace_handler.c
@@ -73,7 +73,7 @@
 	ko = validate_any_object((void *)object);
 	Z_OOPS(K_SYSCALL_VERIFY_MSG(ko != NULL, "object %p access denied",
 				    (void *)object));
-	z_thread_perms_clear(ko, _current);
+	k_thread_perms_clear(ko, _current);
 }
 #include <syscalls/k_object_release_mrsh.c>