ARM: multi_v7_defconfig: Add OPTEE support

STM32MP13 platform relies on OPTEE to boot: Clocks and regulators are
handled in the secure world by OPTEE and exported to the non secure world
(LINUX) thanks to ARM SCMI protocol.

Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>
Link: https://lore.kernel.org/r/20230413072042.30657-1-alexandre.torgue@foss.st.com


Signed-off-by: Arnd Bergmann <arnd@arndb.de>