MAINTAINERS: Update lib/optee with my details

Commit 32ce6179 ("optee: Add lib entries for sharing OPTEE code across
ports") adds code into lib/optee but neglects to update MAINTAINERS to make
me buggable for questions and maintenance.
Signed-off-by: NBryan O'Donoghue <bryan.odonoghue@linaro.org>
Suggested-by: NJens Wiklander <jens.wiklander@linaro.org>

MAINTAINERS

@@ -783,6 +783,11 @@ F:	drivers/tee/
 F:	include/tee.h
 F:	include/tee/
 
+TEE-lib
+M:	Bryan O'Donoghue <bryan.odonoghue@linaro.org>
+S:	Maintained
+F:	lib/optee
+
 UBI
 M:	Kyungmin Park <kmpark@infradead.org>
 M:	Heiko Schocher <hs@denx.de>