drivers: tee: optee: discover OP-TEE services

This change defines resources for OP-TEE service drivers to register
themselves for being bound to when OP-TEE firmware reports the related
service is supported. OP-TEE services are discovered during optee
driver probe sequence which mandates optee driver is always probe once
bound.

Discovery of optee services and binding to related U-Boot drivers is
embedded upon configuration switch CONFIG_OPTEE_SERVICE_DISCOVERY.

Cc: Jens Wiklander <jens.wiklander@linaro.org>
Cc: Patrick Delaunay <patrick.delaunay@foss.st.com>
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
diff --git a/drivers/tee/optee/Kconfig b/drivers/tee/optee/Kconfig
index d030280..9dc65b0 100644
--- a/drivers/tee/optee/Kconfig
+++ b/drivers/tee/optee/Kconfig
@@ -37,6 +37,14 @@
 	help
 	  Enables support for controlling (enabling, provisioning) the
 	  Secure Channel Protocol 03 operation in the OP-TEE SCP03 TA.
+
+config OPTEE_SERVICE_DISCOVERY
+	bool "OP-TEE service discovery"
+	default y
+	help
+	  This implements automated driver binding of OP-TEE service drivers by
+	  requesting OP-TEE firmware to enumerate its hosted services.
+
 endmenu
 
 endif