Add support for managing IRX modules via sysfs.
The driver isn't stable.
Modules are loaded with:
echo "rom1:LIBSD" >/sys/firmware/iopmodules/load_module
echo "rom1:SDRDRV" >/sys/firmware/iopmodules/load_module
echo "libsd.irx" >/sys/firmware/iopmodules/load_module_buffer
echo "sdrdrv.irx" >/sys/firmware/iopmodules/load_module_buffer