KVM: PPC: Book3S HV: Prevent radix guests setting LPCR[TC]

Prevent radix guests setting LPCR[TC]. This bit only applies to hash
partitions.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210412014845.1517916-6-npiggin@gmail.com