tee: add a stub for tee_find_device

Add stub for tee_find_device function when CONFIG_TEE is not activated
to simplify the caller code.

This patch allows to remove the CONFIG_IS_ENABLED(OPTEE) tests
for stm32 platform.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Acked-by: Etienne Carriere <etienne.carriere@inaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/arch/arm/mach-stm32mp/fdt.c b/arch/arm/mach-stm32mp/fdt.c
index a19e954..91330a6 100644
--- a/arch/arm/mach-stm32mp/fdt.c
+++ b/arch/arm/mach-stm32mp/fdt.c
@@ -341,7 +341,6 @@
 	 * when FIP is not used by TF-A
 	 */
 	if (CONFIG_IS_ENABLED(STM32MP15x_STM32IMAGE) &&
-	    CONFIG_IS_ENABLED(OPTEE) &&
 	    !tee_find_device(NULL, NULL, NULL, NULL))
 		stm32_fdt_disable_optee(blob);
 
diff --git a/board/st/common/stm32mp_mtdparts.c b/board/st/common/stm32mp_mtdparts.c
index 8b636d6..1887842 100644
--- a/board/st/common/stm32mp_mtdparts.c
+++ b/board/st/common/stm32mp_mtdparts.c
@@ -119,8 +119,7 @@
 	}
 
 #ifdef CONFIG_STM32MP15x_STM32IMAGE
-	if (!serial && CONFIG_IS_ENABLED(OPTEE) &&
-	    tee_find_device(NULL, NULL, NULL, NULL))
+	if (!serial && tee_find_device(NULL, NULL, NULL, NULL))
 		tee = true;
 #endif
 
diff --git a/include/tee.h b/include/tee.h
index 2ef29bf..44e9cd4 100644
--- a/include/tee.h
+++ b/include/tee.h
@@ -307,11 +307,22 @@
  * Returns a probed TEE device of the first TEE device matched by the
  * match() callback or NULL.
  */
+#if CONFIG_IS_ENABLED(TEE)
 struct udevice *tee_find_device(struct udevice *start,
 				int (*match)(struct tee_version_data *vers,
 					     const void *data),
 				const void *data,
 				struct tee_version_data *vers);
+#else
+static inline struct udevice *tee_find_device(struct udevice *start,
+					      int (*match)(struct tee_version_data *vers,
+							   const void *data),
+					      const void *data,
+					      struct tee_version_data *vers)
+{
+	return NULL;
+}
+#endif
 
 /**
  * tee_get_version() - Query capabilities of TEE device