ps8xxx: Set I2CIDLE command to enter low power mode for ps8805/ps8815
ps8xxx: Set I2CIDLE command to enter low power mode for ps8805/ps8815

PS8751 has the auto sleep function that enters low power mode on its own
in ~2 seconds. But PS8805/PS8815 doesn't have this function. Need to
explicitly set the I2CIDLE command, which is implemented in the tcpci
driver.

BRANCH=None
BUG=b:147302697
TEST=Checked the TCPC enter low power mode, that uses less power.
TEST=Checked PD negotiaion: sinking power, sourcing power, DP dongle.

Change-Id: I9cc9d0a1b8081a8142728f74183bd910614e74b5
Signed-off-by: Wai-Hong Tam <04b587fdf5845741a0c5a8b9cd59ca72d73ef8fc@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2037135
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