usb: gadget: f_mass_storage: If 'ro'/'cdrom' specified, open file as read-only

If we don't need Write access then attempt to open backing file in Read Only
mode instead of bailing out too soon.
Signed-off-by: NRoger Quadros <roger.quadros@nokia.com>
Acked-by: NMichal Nazarewicz <mina86@mina86.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/f_mass_storage.c

@@ -2757,6 +2757,7 @@ static struct fsg_common *fsg_common_init(struct fsg_common *common,
 	for (i = 0, lcfg = cfg->luns; i < nluns; ++i, ++curlun, ++lcfg) {
 		curlun->cdrom = !!lcfg->cdrom;
 		curlun->ro = lcfg->cdrom || lcfg->ro;
+		curlun->initially_ro = curlun->ro;
 		curlun->removable = lcfg->removable;
 		curlun->dev.release = fsg_lun_release;
 		curlun->dev.parent = &gadget->dev;