platform/chrome: cros_ec_sysfs: Expose AP_MODE_ENTRY feature state

platform/chrome: cros_ec_sysfs: Expose AP_MODE_ENTRY feature state

This adds sysfs attribute /sys/class/chromeos/cros_ec/ap_mode_entry
to expose the status of the AP_MODE_ENTRY feature. This attribute
indicate whether the EC requires direction from the Application
Processor (AP) before entering Type-C alternate modes or USB4 mode.
This allows user-space applications to easily determine if the AP needs
to be involved in mode entry.

Signed-off-by: Andrei Kuchynski <akuchynski@chromium.org>
Link: https://lore.kernel.org/r/20250203125947.2701106-3-akuchynski@chromium.org
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>