target-ppc: Convert CPU definitions

Turn the array of model definitions into a set of self-registering QOM
types with their own class_init. Unique identifiers are obtained from
the combination of PVR, SVR and family identifiers; this requires all
alias #defines to be removed from the list. Possibly there are some more
left after this commit that are not currently being compiled.

Prepares for introducing abstract intermediate CPU types for families.

Keep the right-aligned macro line breaks within 78 chars to aid
three-way merges.

Signed-off-by: Andreas Färber <afaerber@suse.de>
target-ppc: Drop duplicate TARGET_PPC64 guard for POWER7

Signed-off-by: Andreas Färber <afaerber@suse.de>
target-ppc: Introduce abstract CPU family types

Instead of assigning *_<family> constants, set .parent to a family type.

Signed-off-by: Andreas Färber <afaerber@suse.de>