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

docs/about/release-information.rst

@@ -69,7 +69,7 @@ after which it will be removed.
 |                                | Date        | after   |                                                         |
 |                                |             | Release |                                                         |
 +================================+=============+=========+=========================================================+
-| None at this time              |             |         |                                                         |
+| STM32MP15_OPTEE_RSV_SHM        |     2.10    |   3.0   | OP-TEE manages its own memory on STM32MP15              |
 +--------------------------------+-------------+---------+---------------------------------------------------------+
 
 Removal of Deprecated Drivers