staging: mmal-vchiq: If the VPU returns an error, don't negate it

There is an enum for the errors that the VPU can return.
port_parameter_get was negating that value, but also using -EINVAL
from the Linux error codes.
Pass the VPU error code as positive values. Should the function
need to pass a Linux failure, then return that as negative.

Signed-off-by: Dave Stevenson <[e-mail]>
Signed-off-by: Jacopo Mondi <[e-mail]>
Signed-off-by: Nicolas Saenz Julienne <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/vc04_services/vchiq-mmal/mmal-vchiq.c

···
 		goto release_msg;
 	}
 
-	ret = -rmsg->u.port_parameter_get_reply.status;
+	ret = rmsg->u.port_parameter_get_reply.status;
+
 	/* port_parameter_get_reply.size includes the header,
 	 * whilst *value_size doesn't.
 	 */