Split the 88100 floating point support code in two files, one for the precise
exceptions, one for the imprecise exceptions. No functional change.
Replace the unmaintainable assembler code responsible for 88100 precise FPU
fault handling with a C wrapper around the softfloat code, as already done for
88110 kernels.

As a bonus, attempting to read or write FPU control registers but fcr62 and
fcr63 in userland will now correctly signal an illegal instruction, instead
of leaving the destination register unchanged and pretending nothing bad
happened.

Be sure to rm m88100_fp.d in your kernel compile directory after updating your
tree.