tee: optee: Fix supplicant based device enumeration

Currently supplicant dependent optee device enumeration only registers
devices whenever tee-supplicant is invoked for the first time. But it
forgets to remove devices when tee-supplicant daemon stops running and
closes its context gracefully. This leads to following error for fTPM
driver during reboot/shutdown:

[   73.466791] tpm tpm0: ftpm_tee_tpm_op_send: SUBMIT_COMMAND invoke error: 0xffff3024

Fix this by adding an attribute for supplicant dependent devices so that
the user-space service can detect and detach supplicant devices before
closing the supplicant:

$ for dev in /sys/bus/tee/devices/*; do if [[ -f "$dev/need_supplicant" && -f "$dev/driver/unbind" ]]; \
      then echo $(basename "$dev") > $dev/driver/unbind; fi done

Reported-by: Jan Kiszka <jan.kiszka@siemens.com>
Closes: https://github.com/OP-TEE/optee_os/issues/6094


Fixes: 5f178bb7 ("optee: enable support for multi-stage bus enumeration")
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Jerome Forissier <jerome.forissier@linaro.org>
[jw: fixed up Date documentation]
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>