pd: Cleanup usb_pd low power idle sleep mask

Add a new define CONFIG_USB_PD_LOW_POWER_IDLE_WHEN_CONNECTED that
indicates the chip should try to go to low power idle even when a PD
connection is established -- this is the current behavior only for
Zinger.

Also, enable and disable the sleep mask bit from tcpc on rx enable /
disable.

BUG=chrome-os-partner:45010
TEST=Manual on glados / glados_pd. Insert Zinger, verify that glados_pd
stays out of low power idle. Remove Zinger, verify that glados_pd
resumes going into low power idle.
BRANCH=None

Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Change-Id: Ie763ae75f4459f56cad47d77d9c25d76358aa484
Reviewed-on: https://chromium-review.googlesource.com/303490
Commit-Ready: Shawn N <shawnn@chromium.org>
Tested-by: Shawn N <shawnn@chromium.org>
Reviewed-by: Alec Berg <alecaberg@chromium.org>
4 files changed