lirc: make chardev nonseekable

There does not seem to be a need for lirc to
allow seeking on the file descriptor, so let's
just disallow this before users start relying
on it.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/media/IR/lirc_dev.c

@@ -460,6 +460,8 @@ error:
 
 	mutex_unlock(&lirc_dev_lock);
 
+	nonseekable_open(inode, file);
+
 	return retval;
 }
 EXPORT_SYMBOL(lirc_dev_fop_open);