clk: ep93xx: add module license

When configured as a lodable module, this driver produces
a build time warning:

ERROR: modpost: missing MODULE_LICENSE() in drivers/clk/clk-ep93xx.o

All all three tags for license, author and description based
on the header.
Acked-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/clk/clk-ep93xx.c

@@ -844,3 +844,7 @@ static struct auxiliary_driver ep93xx_clk_driver = {
 	.id_table	= ep93xx_clk_ids,
 };
 module_auxiliary_driver(ep93xx_clk_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Nikita Shubin <nikita.shubin@maquefel.me>");
+MODULE_DESCRIPTION("Clock control for Cirrus EP93xx chips");