Add UCLASS_TEE for Trusted Execution Environment

Adds a uclass to interface with a TEE (Trusted Execution Environment).

A TEE driver is a driver that interfaces with a trusted OS running in
some secure environment, for example, TrustZone on ARM cpus, or a
separate secure co-processor etc.

The TEE subsystem can serve a TEE driver for a Global Platform compliant
TEE, but it's not limited to only Global Platform TEEs.

The over all design is based on the TEE subsystem in the Linux kernel,
tailored for U-Boot.

Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Igor Opaniuk <igor.opaniuk@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/MAINTAINERS b/MAINTAINERS
index 6b4d00a..dac76e0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -629,6 +629,12 @@
 S:	Orphaned (Since 2016-02)
 T:	git git://git.denx.de/u-boot-tq-group.git
 
+TEE
+M:	Jens Wiklander <jens.wiklander@linaro.org>
+S:	Maintained
+F:	drivers/tee/
+F:	include/tee.h
+
 UBI
 M:	Kyungmin Park <kmpark@infradead.org>
 M:	Heiko Schocher <hs@denx.de>