powerpc/ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names

powerpc/ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names

Instead of having the core code guess the note name for each regset,
use USER_REGSET_NOTE_TYPE() to pick the correct name from elf.h.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Akihiko Odaki <akihiko.odaki@daynix.com>
Cc: linuxppc-dev@lists.ozlabs.org
Reviewed-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>
Link: https://lore.kernel.org/r/20250701135616.29630-16-Dave.Martin@arm.com
Signed-off-by: Kees Cook <kees@kernel.org>