usb: typec: tcpm: avoid graph warning

When using a devicetree as described in commit d56de8c9 ("usb:
typec: tcpm: try to get role switch from tcpc fwnode"), the kernel
will print an error when probing the TCPM driver, which looks
similar to this:

OF: graph: no port node found in /i2c@feac0000/usb-typec@22

This is a false positive, since the code first tries to find a ports
node for the device and only then checks the fwnode. Fix this by
swapping the order.

Note, that this will now generate a error message for devicetrees with
a role-switch ports node directly in the TCPM node instead of in the
connectors sub-node, before falling back to the legacy behaviour. These
devicetrees generate warnings when being checked against the bindings,
and should be fixed.

Fixes: d56de8c9 ("usb: typec: tcpm: try to get role switch from tcpc fwnode")
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>