uml: mmapper_kern needs MODULE_LICENSE

Add missing MODULE_LICENSE():

WARNING: modpost: missing MODULE_LICENSE() in arch/um/drivers/mmapper_kern.o
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Greg Lonnon <glonnon@ridgerun.com>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/um/drivers/mmapper_kern.c

@@ -137,3 +137,4 @@ module_exit(mmapper_exit);
 
 MODULE_AUTHOR("Greg Lonnon <glonnon@ridgerun.com>");
 MODULE_DESCRIPTION("DSPLinux simulator mmapper driver");
+MODULE_LICENSE("GPL");