tty: move linux/gsmmux.h to uapi

linux/gsmmux.h defines a user interface and therefore should be
installed with other headers.

Make the file include:
* linux/if.h for IFNAMSIZ
* linux/ioctl.h for _IO* macros

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/uapi/linux/Kbuild

@@ -138,6 +138,7 @@ header-y += genetlink.h
 header-y += gen_stats.h
 header-y += gfs2_ondisk.h
 header-y += gigaset_dev.h
+header-y += gsmmux.h
 header-y += hdlcdrv.h
 header-y += hdlc.h
 header-y += hdreg.h

include/uapi/linux/gsmmux.h

@@ -1,6 +1,9 @@
 #ifndef _LINUX_GSMMUX_H
 #define _LINUX_GSMMUX_H
 
+#include <linux/if.h>
+#include <linux/ioctl.h>
+
 struct gsm_config
 {
 	unsigned int adaption;