drivers/firmware/sigma.c needs MODULE_LICENSE

Fix module tainting message:

  sigma: module license 'unspecified' taints kernel.
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/firmware/sigma.c

@@ -11,6 +11,7 @@
 #include <linux/firmware.h>
 #include <linux/kernel.h>
 #include <linux/i2c.h>
+#include <linux/module.h>
 #include <linux/sigma.h>
 
 /* Return: 0==OK, <0==error, =1 ==no more actions */
@@ -113,3 +114,5 @@ int process_sigma_firmware(struct i2c_client *client, const char *name)
 	return ret;
 }
 EXPORT_SYMBOL(process_sigma_firmware);
+
+MODULE_LICENSE("GPL");