i2c: acorn: add MODULE_LICENSE tag

As of v4.15, Kbuild warns about missing MODULE_LICENSE tags:

WARNING: modpost: missing MODULE_LICENSE() in drivers/i2c/busses/i2c-acorn.o

This adds a license, author and description tag, matching the
comment at the start of the acorn i2c driver.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-acorn.c

@@ -94,3 +94,7 @@ static int __init i2c_ioc_init(void)
 }
 
 module_init(i2c_ioc_init);
+
+MODULE_AUTHOR("Russell King <linux@armlinux.org.uk>");
+MODULE_DESCRIPTION("ARM IOC/IOMD i2c driver");
+MODULE_LICENSE("GPL v2");