[media] rc-main: allow raw protocol drivers to restrict the allowed protos

On some hardware (au0828/au8522), the hardware is broken with
regards to the initial pulse detection. So, the driver needs to
produce a fake start pulse. That limits the acceptable protocols,
as it is not possible to produce a fake pulse that would cover
all supported protocols.

So, allow the driver to explicitly set the allowed protocols.

If the driver doesn't specify, keep the old behavior.
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/rc/rc-main.c

@@ -859,10 +859,9 @@ static ssize_t show_protocols(struct device *device,
 
 	if (fattr->type == RC_FILTER_NORMAL) {
 		enabled = dev->enabled_protocols;
-		if (dev->raw)
+		allowed = dev->allowed_protocols;
+		if (dev->raw && !allowed)
 			allowed = ir_raw_get_allowed_protocols();
-		else
-			allowed = dev->allowed_protocols;
 	} else {
 		enabled = dev->enabled_wakeup_protocols;
 		allowed = dev->allowed_wakeup_protocols;