typec: tcpm: add starting value for drp toggling

As DRP port autonomously toggles the Rp/Rd need a start value to
begin with, so add one parameter for it in tcpm_start_drp_toggling.

Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Li Jun <jun.li@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>