target-ppc: Move POWER7/8 CFAR/DSCR/CTRL/PPR/PCR SPR registration to helpers

target-ppc: Move POWER7/8 CFAR/DSCR/CTRL/PPR/PCR SPR registration to helpers

This moves SCFAR/DSCR/CTRL/PPR/PCR PRs to helpers. Later these helpers
will be called from generalized init_proc_book3s_64().

This switches init_proc_POWER7() to use generalized gen_spr_book3s_common()
which registers CRTL SPR under slightly different names. No change in
behaviour or non-debug output is expected.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>