cr50: Wake on AC detect edges
cr50: Wake on AC detect edges

Currently, we only use the AC detect interrupt for battery cutoff
support on detachable devices, and we use the RDD detect interrupt for
waking Cr50 from deep sleep.  However, Eve accidentally detects RDD
when the EC is off, so this is not a reliable signal - particularly if
Cr50 is explicitly driving EC reset.

Enable the AC detect interrupt all the time, and defer sleep for 5
seconds when it transitions.  This will have a negligible effect on
overall power (since AC is not normally transitioning) and will allow
the RDD detect code to be simplified.

BUG=b:64799106
BRANCH=cr50
TEST=manually pull DIOR5 up and down; see AC interrupt debug output.
     idle d, wait for sleep, then wiggle DIOR5 and see that cr50 wakes.

Change-Id: I7551f25e27a79573bf4527d8c38994634df621ec
Signed-off-by: Randall Spangler <62698fdbb84d1779579ee80c3f39fac22017e5bc@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/619319
Reviewed-by: Aseda Aboagye <12c9b286316a940fd31c24070da5ab64cdd4d0e7@chromium.org>

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