powerpc/math-emu: Fix decoding of some instructions

The decoding of some instructions such as fsqrt{s} was incorrect,
using the wrong registers, and thus could not work.

This fixes it and also adds a couple of place holders for missing
instructions.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --cc arch/powerpc/math-emu/Makefile
Simple merge

diff --cc arch/powerpc/math-emu/fre.c
Simple merge

diff --cc arch/powerpc/math-emu/frsqrtes.c
Simple merge

diff --cc arch/powerpc/math-emu/math.c
Simple merge