board: ti: README: Update OP-TEE binary name

The OP-TEE binary to use is renamed to v2 as the v1 binary has been
deprecated and is no longer built by default.

Reported-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Andrew F. Davis <afd@ti.com>
2 files changed