usb: typec: Ensure USB_ROLE_SWITCH is set as a dependency for tps6598x

usb: typec: Ensure USB_ROLE_SWITCH is set as a dependency for tps6598x

When I switched on USB role switching for the tps6598x I completely forgot
to add the Kconfig dependency.

Ensure USB_ROLE_SWITCH is selected to prevent the typs6598x driver being
compiled in but the role-switch driver being compiled as a module, leading
to link error.

Suggested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20200520153617.610909-1-bryan.odonoghue@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>