usb_pd_dual_role: fix dbz when parsing PDO
usb_pd_dual_role: fix dbz when parsing PDO

This path was hitted by ec_usb_pd_fuzzer.

BUG=b:198325864
TEST=cros_fuzz --board=amd64-generic reproduce \
  --fuzzer ec_usb_pd_fuzzer \
  --testcase /build/amd64-generic/tmp/\
  clusterfuzz-testcase-minimized-ec_usb_pd_fuzzer-6223286274490368 \
  --package chromeos-ec --build-type ubsanh
BRANCH=main

Change-Id: I9575a890bba16145f3d92d1ecc84afcf12d72d67
Signed-off-by: Eric Yilun Lin <2f2733c7206ea2b76bd2db1905cc5e8a75841c48@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3159850
Tested-by: Eric Yilun Lin <2f2733c7206ea2b76bd2db1905cc5e8a75841c48@google.com>
Reviewed-by: Daisuke Nojiri <fd5f93af191bf7e8f73ea71cc3c0f66b41b1dd49@chromium.org>
Commit-Queue: Eric Yilun Lin <2f2733c7206ea2b76bd2db1905cc5e8a75841c48@google.com>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec