ARM: SAMSUNG: using vsnprintf instead of vsprintf for the limit buffer length 256

the buff is 256 limited, so need use vsnprintf instead of vsprintf
Signed-off-by: Chen Gang <gang.chen@asianux.com>
Cc: Ben Dooks <ben@fluff.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/plat-samsung/pm.c

@@ -51,7 +51,7 @@ void s3c_pm_dbg(const char *fmt, ...)
 	char buff[256];
 
 	va_start(va, fmt);
-	vsprintf(buff, fmt, va);
+	vsnprintf(buff, sizeof(buff), fmt, va);
 	va_end(va);
 
 	printascii(buff);