arm64, mailmap: update email address for Peter Collingbourne

arm64, mailmap: update email address for Peter Collingbourne

I am no longer at Google.

Link: https://lore.kernel.org/20260718172923.8297-1-peter@pcc.me.uk
Signed-off-by: Peter Collingbourne <peter@pcc.me.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jakub Kacinski <kuba@kernel.org>
Cc: Martin Kepplinger <martink@posteo.de>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>