That particular patch just enables the IR option in the kernel, as well some driver (lirc) stuff for the transmitter, nothing RX51 specific about any receive sensor at all unfortunately.

You shouldn't need to do anything to make this work, the module should already be present (modprobe -l | awk /lirc/ ...if you see lirc_rx51.ko you're good)

The modinfo stuff:

+MODULE_DESCRIPTION("LIRC TX driver for Nokia RX51");
+MODULE_AUTHOR("Nokia Corporation");