zephyr: IWYU Include header for PWR_SIGNAL_ENUM
zephyr: IWYU Include header for PWR_SIGNAL_ENUM

PWR_SIGNAL_ENUM is defined in power_signals.h, so add include for that
header.

BRANCH=None
BUG=b:247100970
TEST=zmake build -a
TEST=./twister --clobber -v -i
TEST=make -j$(nproc) buildall_only runtests
TEST=zmake compare-builds

Signed-off-by: Jeremy Bettis <4df7b5147fee087dca33c181f288ee7dbf56e022@google.com>
Change-Id: I426432b253d41516fe5158198fb7763f9b64d7dc
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/4043351
Tested-by: Fernando Perea <001697a9e5e1e6388ea298ca44c2ff180edce42a@gmail.com>
Auto-Submit: Jeremy Bettis <4df7b5147fee087dca33c181f288ee7dbf56e022@chromium.org>
Reviewed-by: Fernando Perea <001697a9e5e1e6388ea298ca44c2ff180edce42a@gmail.com>
Commit-Queue: Jeremy Bettis <4df7b5147fee087dca33c181f288ee7dbf56e022@chromium.org>
Code-Coverage: Zoss <345cf107e82c70959d46f59d98bddc98ce458aff@prod.google.com>
Tested-by: Jeremy Bettis <4df7b5147fee087dca33c181f288ee7dbf56e022@chromium.org>
Reviewed-by: Tristan Honscheid <1e17951ff5ffc8afe254954c03de64afef62fe52@google.com>
Code-Coverage: Fernando Perea <001697a9e5e1e6388ea298ca44c2ff180edce42a@gmail.com>

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