docs(stm32mp15): mark STM32MP15_OPTEE_RSV_SHM deprecated

TF-A is no more in charge of configuring OP-TEE shared memory.
Set the STM32MP15_OPTEE_RSV_SHM flag as deprecated (as well as the code
depending on it).

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: I863d9a1e45e0bfc2f45d9bd84b90d626738934ab
1 file changed