usb: pd: Notify charger when PR Swap is in progress

Charger driver needs to know when PR Swap is happening in
order to avoid resetting state when the disconnect (which
is expected) occurs. Utilize the new power supply PR_SWAP
property to notify whenever PD is in PR Swap.

Change-Id: I13fdbd4a3cf3e0716d48d1268795189f6b064598
Signed-off-by: Jack Pham <jackp@codeaurora.org>