target-sparc: Migrate CWP and PIL for SPARC64

target-sparc: Migrate CWP and PIL for SPARC64

In SPARC32 the env->cwp and env->psrpil state is part of the PSR
register, and gets migrated as part of that register.
In SPARC64 this state is in separate CWP and PIL registers, but we
were not doing anything to migrate those.

Add the missing fields to the migration vmstate (which is a
migration break, but without these fields migration is completely
broken anyway).

This change means that trying a save/load of a SPARC64 target at
the boot rom prompt now produces a system which at least responds
to keyboard input after the restore.

Reported-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>