mailmap: add entries for past lives

Update old emails for my current work email.
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Link: https://lore.kernel.org/r/20230717193242.43670-1-shannon.nelson@amd.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

.mailmap

@@ -453,6 +453,8 @@ Sebastian Reichel <sre@kernel.org> <sre@debian.org>
 Sedat Dilek <sedat.dilek@gmail.com> <sedat.dilek@credativ.de>
 Seth Forshee <sforshee@kernel.org> <seth.forshee@canonical.com>
 Shannon Nelson <shannon.nelson@amd.com> <snelson@pensando.io>
+Shannon Nelson <shannon.nelson@amd.com> <shannon.nelson@intel.com>
+Shannon Nelson <shannon.nelson@amd.com> <shannon.nelson@oracle.com>
 Shiraz Hashim <shiraz.linux.kernel@gmail.com> <shiraz.hashim@st.com>
 Shuah Khan <shuah@kernel.org> <shuahkhan@gmail.com>
 Shuah Khan <shuah@kernel.org> <shuah.khan@hp.com>