usb: dwc3-msm: Improve extcon handling

In order to support type-c and micro-AB connectors, driver
depends upon power supply property
POWER_SUPPLY_CONNECTOR_MICRO_USB to query connector type.
Based upon type appropriate fixed index is used to get the
extcon device. On some targets power supply property may not
be available. In order to support different connector type
on such targets register for vbus and id notification on all
available extcon devices. This allows usb driver to be agnostic
to connector type.

Change-Id: Ia65a659b4c7db472ecb0499c0ee1f98201da4059
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
Signed-off-by: Jack Pham <jackp@codeaurora.org>