usb: phy: show USB charger type for user

Current USB charger framework only shows charger state for user, but the
user may also need charger type for further use, add support for it.

Signed-off-by: Peter Chen <peter.chen@nxp.com>
Link: https://lore.kernel.org/r/1579145333-1657-1-git-send-email-peter.chen@nxp.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>