Add a helper function to initiate AP reset through Embedded Controller (EC). BUG=b:162290856 TEST=Ensure that the EC resets AP on boards where the command is supported. Change-Id: I01d7dfec72a8a3f6d2c4844bc062672e494860d8 Signed-off-by: Karthikeyan Ramasubramanian <kramasub@google.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/44188 Reviewed-by: Furquan Shaikh <furquan@google.com> Reviewed-by: Nick Vaccaro <nvaccaro@google.com> Reviewed-by: Edward O'Callaghan <quasisec@chromium.org> Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org> Reviewed-by: Justin TerAvest <teravest@chromium.org> Reviewed-by: Angel Pons <th3fanbus@gmail.com> Tested-by: build bot (Jenkins) <no-reply@coreboot.org>