Shared Reed-Solomon ECC library

Shared Reed-Solomon ECC library

The attached patch contains a shared Reed-Solomon Library analogous to
the shared zlib.

(N)AND FLASH is gaining popularity and there are a lot of ASIC/SoC/FPGA
controllers around which implement hardware support for Reed-Solomon
error correction. As usual they use different implementations
(polynomials etc.). So it's obvious to use a shared library for the
common tasks of error correction.

A short scan through the kernel revealed that at least the ftape driver
uses Reed-Solomon error correction. It could be easily converted to use
the shared library code.

The encoder/decoder code is lifted from the GPL'd userspace RS-library
written by Phil Karn. I modified/wrapped it to provide the different
functions which we need in the MTD/NAND code.

The library is tested in extenso under various MTD/NAND configurations.

The lib should be usable for other purposes right out of the box.
Adjustment for currently not implemented functionality is an easy task.

I'm willing to take the maintainership of the library.

Signed-Off-By: Thomas Gleixner <tglx@linutronix.de>
Signed-Off-By: David Woodhouse <dwmw2@infradead.org>
"No objections at all. Just keep the authorship notices." -- Phil Karn