target-arm: Reinstate display of VFP registers in cpu_dump_state

target-arm: Reinstate display of VFP registers in cpu_dump_state

Reinstate the display of VFP registers in cpu_dump_state(), if
the CPU has them (this code had been #if 0'd out a for a long time).
We drop the attempt ot display the values as floating point, since
this makes assumptions about the host 'float' and 'double' formats
and is not done by eg the i386 cpu_dump_state().
This display is gated on the CPU_DUMP_FPU flag, as for x86.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>