platform/chrome: cros_usbpd_notify: defer probe when parent EC driver isn't ready

platform/chrome: cros_usbpd_notify: defer probe when parent EC driver isn't ready

The cros-usbpd-notify-acpi probe currently does not exit when it fails
to get a pointer to the ChromeOS EC device. It is expected behavior on
older devices, where GOOG0004 is not a parent of GOOG0003.

Update the cros-usbpd-notify-acpi probe to check for a GOOG0004 parent
fwnode. If the device has correct device hierarchy and fails to get an
EC device pointer, defer the probe function.

Signed-off-by: Jameson Thies <jthies@google.com>
Reviewed-by: Benson Leung <bleung@chromium.org>
Link: https://lore.kernel.org/r/20251007004043.4109957-1-jthies@google.com
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>