[POWERPC] ppc32: Fix errata for 603 CPUs

603 CPUs have the same issue that some 750 CPUs have in that they can crash
in funny ways if a store from an FPU register instruction is executed on a
register that has never been initialized since power on.  This patch fixes
it by making sure all FP registers have been properly initialized at kernel
boot.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>