tee: optee: sync cache on pre-reloc OP-TEE invocation

tee: optee: sync cache on pre-reloc OP-TEE invocation

This change ensures both U-Boot and OP-TEE see the same content
from shared memory when OP-TEE is invoked prior U-Boot relocation.

This change is required since U-Boot may execute with data cache off
while OP-TEE always enables cache on memory shared with U-Boot.

Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>