SERIAL: MIPS DECstation zs.c driver needs module.h

This driver is a module and needs module.h, otherwise it will break when we
remove a bogus usage of module.h from one of the other MIPS headers.

Signed-off-by: Paul Gortmaker <[e-mail]>
Cc: [e-mail]
Patchwork: https://patchwork.linux-mips.org/patch/3446/
Signed-off-by: Ralf Baechle <[e-mail]>

drivers/tty/serial/zs.c

···
 #include <linux/ioport.h>
 #include <linux/irqflags.h>
 #include <linux/kernel.h>
+#include <linux/module.h>
 #include <linux/major.h>
 #include <linux/serial.h>
 #include <linux/serial_core.h>