ARM: prima2: rtciobrg: fix the typo about license

we are marking GPL v2 in head comments, but MODULE_LICENSE is declaring GPL.
Signed-off-by: Barry Song <Baohua.Song@csr.com>

arch/arm/mach-prima2/rtciobrg.c

@@ -137,4 +137,4 @@ postcore_initcall(sirfsoc_rtciobrg_init);
 MODULE_AUTHOR("Zhiwu Song <zhiwu.song@csr.com>, "
 		"Barry Song <baohua.song@csr.com>");
 MODULE_DESCRIPTION("CSR SiRFprimaII rtc io bridge");
-MODULE_LICENSE("GPL");
+MODULE_LICENSE("GPL v2");