target/ppc: Remove fallback 64k pagesize information

target/ppc: Remove fallback 64k pagesize information

CPU definitions for cpus with the 64-bit hash MMU can include a table of
available pagesizes.  If this isn't supplied ppc_cpu_instance_init() will
fill it in a fallback table based on the POWERPC_MMU_64K bit in mmu_model.

However, it turns out all the cpus which support 64K pages already include
an explicit table of page sizes, so there's no point to the fallback table
including 64k pages.

That removes the only place which tests POWERPC_MMU_64K, so we can remove
it.  Which in turn allows some logic to be removed from
kvm_fixup_page_sizes().

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>