macintosh/ams/ams: Add header file macro definition

Add header file macro definition.
Signed-off-by: Li zeming <zeming@nfschina.com>
[mpe: Add endif comment]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220707015352.3391-1-zeming@nfschina.com

drivers/macintosh/ams/ams.h

 /* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _AMS_H
+#define _AMS_H
+
 #include <linux/i2c.h>
 #include <linux/input.h>
 #include <linux/kthread.h>
@@ -69,3 +72,5 @@ extern int ams_i2c_init(struct device_node *np);
 
 extern int ams_input_init(void);
 extern void ams_input_exit(void);
+
+#endif /* _AMS_H */