usb: chipidea: Consolidate extcon notifiers

The two extcon notifiers are almost the same except for the
variable name for the cable structure and the id notifier inverts
the cable->state logic. Make it the same and replace two
functions with one to save some lines. This also makes it so that
the id cable state is true when the id pin is pulled low, so we
change the name of ->state to ->connected to properly reflect
that we're interested in the cable being connected.

Acked-by: Peter Chen <peter.chen@nxp.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Ivan T. Ivanov" <iivanov.xz@gmail.com>
Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>
Signed-off-by: Peter Chen <peter.chen@nxp.com>