staging: sm750fb: update license

The driver was actually released with BSD license. It also gained GPL
when it was submitted to be included in the kernel.

Cc: Teddy Wang <teddy.wang@siliconmotion.com>
Cc: gzhou1 <guojian.zhou@windriver.com>
Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/sm750fb/sm750.c

@@ -1243,4 +1243,4 @@ MODULE_PARM_DESC(g_option,
 MODULE_AUTHOR("monk liu <monk.liu@siliconmotion.com>");
 MODULE_AUTHOR("Sudip Mukherjee <sudip@vectorindia.org>");
 MODULE_DESCRIPTION("Frame buffer driver for SM750 chipset");
-MODULE_LICENSE("GPL v2");
+MODULE_LICENSE("Dual BSD/GPL");