Add support for printing the PIDR/TIDR for ISA 300 and PSSCR and PTCR
in ISA 3.0 hypervisor mode.

SPRN_PSSCR_PR is the privileged mode access and is used when we are
not in hypervisor mode.
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
[mpe: Split out of larger patch]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>