platform/chrome: cros_ec_typec: Check for EC driver

The EC driver may not be initialized when cros_typec_probe is called,
particulary when CONFIG_CROS_EC_CHARDEV=m.

Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Link: https://lore.kernel.org/r/20220404041101.6276-1-akihiko.odaki@gmail.com


Signed-off-by: Prashant Malani <pmalani@chromium.org>