DEVELOPERS: update etienne carriere e-mail address

Updates my e-mail address.

Signed-off-by: Etienne Carriere <etienne.carriere@foss.st.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

DEVELOPERS

@@ -862,7 +862,7 @@ F:	package/szip/
 N:	Esben Haabendal <esben@haabendal.dk>
 F:	package/python-kiwisolver/
 
-N:	Etienne Carriere <etienne.carriere@linaro.org>
+N:	Etienne Carriere <etienne.carriere@foss.st.com>
 F:	boot/optee-os/
 F:	package/optee-client/
 F:	package/optee-examples/