pit: leave 1.35V rail on during warm reboot
pit: leave 1.35V rail on during warm reboot

This maintains the contents of AP RAM during the warm reboot.

BUG=chrome-os-partner:21483
BRANCH=pit
TEST=from u-boot prompt,

Peach # mm 41f00000
41f00000: 00000000 ? 9
41f00004: 00000000 ? 9
41f00008: 00000000 ? 9
41f0000c: 00000000 ? 9
41f00010: 00000000 ? 9
41f00014: 00000000 ? 9
41f00018: 00000000 ? 9
41f0001c: 00000000 ? 9
41f00020: 00000000 ? 9
41f00024: 00000000 ? 9
41f00028: 00000000 ? 9
41f0002c: 00000000 ? 9
41f00030: 00000000 ? 9
41f00034: 00004000 ? 9
41f00038: 00000000 ? 9
41f0003c: 00000000 ? 9
41f00040: 00000000 ? .
Peach # md 41f00000
41f00000: 00000009 00000009 00000009 00000009    ................
41f00010: 00000009 00000009 00000009 00000009    ................
41f00020: 00000009 00000009 00000009 00000009    ................
41f00030: 00000009 00000009 00000009 00000009    ................

Then Alt+VolUp+R.  Then repeat md command at u-boot prompt.

Change-Id: I07de4df2fe4c4dd86b88bbd208e1fb87860fa9d5
Signed-off-by: Randall Spangler <62698fdbb84d1779579ee80c3f39fac22017e5bc@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/65227
Reviewed-by: Julius Werner <4d12f06cff3725783b352157673a720bc67c4afe@chromium.org>

eatbyte/chromium-ec,fourier49/BIZ_EC,fourier49/BZ_DEV_EC,fourier49/BIZ_EC,md5555/ec,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,fourier49/BZ_DEV_EC,mtk09422/chromiumos-platform-ec,thehobn/ec,eatbyte/chromium-ec,coreboot/chrome-ec,longsleep/ec,fourier49/BZ_DEV_EC,gelraen/cros-ec,fourier49/BIZ_EC,akappy7/ChromeOS_EC_LED_Diagnostics,longsleep/ec,coreboot/chrome-ec,coreboot/chrome-ec,mtk09422/chromiumos-platform-ec,coreboot/chrome-ec,alterapraxisptyltd/chromium-ec,md5555/ec,eatbyte/chromium-ec,thehobn/ec,gelraen/cros-ec,akappy7/ChromeOS_EC_LED_Diagnostics,thehobn/ec,mtk09422/chromiumos-platform-ec,coreboot/chrome-ec,alterapraxisptyltd/chromium-ec,akappy7/ChromeOS_EC_LED_Diagnostics,md5555/ec,akappy7/ChromeOS_EC_LED_Diagnostics,alterapraxisptyltd/chromium-ec,md5555/ec,longsleep/ec,alterapraxisptyltd/chromium-ec,eatbyte/chromium-ec,mtk09422/chromiumos-platform-ec,fourier49/BIZ_EC,fourier49/BZ_DEV_EC,gelraen/cros-ec,gelraen/cros-ec,thehobn/ec,longsleep/ec