usb: typec: tcpm: Raise vdm_sm_running flag only when VDM SM is running

usb: typec: tcpm: Raise vdm_sm_running flag only when VDM SM is running

If the port is going to send Discover_Identity Message, vdm_sm_running
flag was intentionally set before entering Ready States in order to
avoid the conflict because the port and the port partner might start
AMS at almost the same time after entering Ready States.

However, the original design has a problem. When the port is doing
DR_SWAP from Device to Host, it raises the flag. Later in the
tcpm_send_discover_work, the flag blocks the procedure of sending the
Discover_Identity and it might never be cleared until disconnection.

Since there exists another flag send_discover representing that the port
is going to send Discover_Identity or not, it is enough to use that flag
to prevent the conflict. Also change the timing of the set/clear of
vdm_sm_running to indicate whether the VDM SM is actually running or
not.

Fixes: c34e85fa69b9 ("usb: typec: tcpm: Send DISCOVER_IDENTITY from dedicated work")
Cc: stable <stable@vger.kernel.org>
Cc: Badhri Jagan Sridharan <badhri@google.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Kyle Tso <kyletso@google.com>
Link: https://lore.kernel.org/r/20210826124201.1562502-1-kyletso@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>