samus: Fix flaw in power up inhibit
samus: Fix flaw in power up inhibit

Power up inhibit is intended to stop the AP from booting when the
battery is in certain states. It works most of the time, but sometimes
IN_PCH_SLP_S5_DEASSERTED is already set by the time we get to S5 and we
incorrectly boot the AP.

Thinking about this more, it's better to check the battery state in G3,
before we transition to S5, to prevent the needless transition back to
G3 if power up is indeed inhibited.

BUG=chrome-os-partner:35182
TEST=Manual on Samus. Drain battery to 1% and attach charger. Press
power button multiple times and verify that AP doesn't boot. Charge
better to 2% and press power button. Verify that AP boots.
BRANCH=Samus

Signed-off-by: Shawn Nematbakhsh <5259333ce42e3ace6a73988cec7115ed9d3a661a@chromium.org>
Change-Id: Ib03c3f707f9d90d0a9cb07ada3738d00e2728c32
Reviewed-on: https://chromium-review.googlesource.com/239352
Reviewed-by: Duncan Laurie <70662b43bc1a20b57ded72a2b08be88dd0da4841@chromium.org>
Reviewed-by: Alec Berg <1a4429eeda29095a12e19a73405f80f5b7f37a63@chromium.org>

coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,coreboot/chrome-ec,fourier49/BZ_DEV_EC,eatbyte/chromium-ec,eatbyte/chromium-ec,mtk09422/chromiumos-platform-ec,akappy7/ChromeOS_EC_LED_Diagnostics,mtk09422/chromiumos-platform-ec,mtk09422/chromiumos-platform-ec,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,md5555/ec,fourier49/BZ_DEV_EC,coreboot/chrome-ec,md5555/ec,fourier49/BZ_DEV_EC,coreboot/chrome-ec,eatbyte/chromium-ec,fourier49/BIZ_EC,md5555/ec,eatbyte/chromium-ec,akappy7/ChromeOS_EC_LED_Diagnostics,mtk09422/chromiumos-platform-ec,fourier49/BZ_DEV_EC,akappy7/ChromeOS_EC_LED_Diagnostics,fourier49/BIZ_EC,md5555/ec,fourier49/BIZ_EC,fourier49/BIZ_EC