tty/module.c: include proper header for INIT_C_CC definition

In upstream commit c9874d3ffeaf (termios: start unifying non-UAPI
parts of asm/termios.h), the INIT_C_CC definition was moved to a new
header, termios_internal.h. So we must include that header to get that
macro, but conditionally, since the header does not exist in older
kernels.

tty/module.c

@@ -45,6 +45,10 @@
 #include <linux/uaccess.h>
 #include <linux/slab.h>
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 1, 0)
+#include <linux/termios_internal.h>
+#endif
+
 #include "../master/globals.h"
 #include "../include/ectty.h"