usb: typec: intel_pmc_mux: Expose IOM port status to debugfs

IOM status has a crucial role during debugging to check the
current state of the type-C port.
There are ways to fetch the status, but all those require the
IOM port status offset, which could change with platform.

Make a debugfs directory for intel_pmc_mux and expose the status
under it per port basis.

Signed-off-by: Rajat Khandelwal <rajat.khandelwal@linux.intel.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Message-ID: <20230531105050.638250-1-rajat.khandelwal@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>