power: smb138x-charger: Add support of extcon based notifications

Add extcon support in charger driver which is used to notify cable
state(device/host mode, CC orientation) to USB driver.

CRs-Fixed: 2086422
Change-Id: I68448059c4ef2089881623f074dc1b578fb36f3d
Signed-off-by: Ankit Sharma <ansharma@codeaurora.org>