Config: Add stm targets in single entry point

This patch allows to group all stm targets in single cmake entry point.
The stm TARGET_PLATFORM should prefix by "STM".
stm platforms supports CoreIPC, CoreIPCTfmLevel2 and RegressionIPCTfmLevel2
Build with GNUARM toolchain.

Change-Id: I6535420b2304c18f2ab260620c38fef632eb7488
Signed-off-by: Ludovic Barre <ludovic.barre@st.com>
Signed-off-by: Michel Jaouen <michel.jaouen@st.com>
diff --git a/docs/user_guides/tfm_build_instruction.rst b/docs/user_guides/tfm_build_instruction.rst
index de910ad..3f5d0f9 100644
--- a/docs/user_guides/tfm_build_instruction.rst
+++ b/docs/user_guides/tfm_build_instruction.rst
@@ -265,6 +265,12 @@
             See :doc:`Cypress PSoC 64 platform specifics </platform/ext/target/cypress/psoc64/cypress_psoc64_spec>`
           - DesignStart FPGA on Cloud: Cortex-M33 based platform (SSE-200_AWS platform)
             ``-DTARGET_PLATFORM=SSE-200_AWS``
+          - DISCO_L562QE board (Cortex-M33 STM32L562)
+            ``-DTARGET_PLATFORM=STM_DISCO_L562QE``
+            See :doc:`STM32L5xx platform specifics </platform/ext/target/stm/stm32l5xx/readme>`
+          - NUCLEO_L552ZE_Q (Cortex-M33 STM32L552)
+            ``-DTARGET_PLATFORM=SSTM_NUCLEO_L552ZE_Q``
+            See :doc:`STM32L5xx platform specifics </platform/ext/target/stm/stm32l5xx/readme>`
 
    * - -DCOMPILER=<compiler name>
      - Specifies the compiler toolchain