platform/chrome: cros_ec_typec: allow deferred probe of switch handles

`fwnode_typec_{retimer,mux,switch}_get()` could return `-EPROBE_DEFER`,
which is called from `cros_typec_get_switch_handles`. When this happens,
it does not indicate absence of switches; instead, it only hints that
probing of switches should occur at a later time.

Progagate `-EPROBE_DEFER` to upper layer logic so that they can re-try
probing switches as a better time.

Signed-off-by: Victor Ding <victording@chromium.org>
Reviewed-by: Benson Leung <bleung@chromium.org>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20230124075555.v3.1.I6c0a089123fdf143f94ef4cca8677639031856cf@changeid
Signed-off-by: Prashant Malani <pmalani@chromium.org>