serial: max3100: Convert to_max3100_port() to be static inline

As Jiri rightfully pointed out the current to_max3100_port() macro
implementation is fragile in a sense that it expects the variable
name to be port, otherwise it blow up the build.

Change this to be static inline to prevent bad compilation.

Suggested-by: Jiri Slaby <[e-mail]>
Signed-off-by: Andy Shevchenko <[e-mail]>
Reviewed-by: Ilpo Järvinen <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/tty/serial/max3100.c

···
 	struct timer_list	timer;
 };
 
-#define to_max3100_port(port)	container_of(port, struct max3100_port, port)
+static inline struct max3100_port *to_max3100_port(struct uart_port *port)
+{
+	return container_of(port, struct max3100_port, port);
+}
 
 static struct max3100_port *max3100s[MAX_MAX3100]; /* the chips */
 static DEFINE_MUTEX(max3100s_lock);		   /* race on probe */