Platform: Add mps3/an547 platform

Add support for AN547, an MPS3 FPGA platform based on Corstone SSE-300
with Ethos-U55, and unify it with the already existing support of
Corstone-300 Ethos-U55 Ecosystem FVP.

Change-Id: I9cbb0167e61244214a8eeb5a55165c296af03ef7
Signed-off-by: Gabor Toth <gabor.toth@arm.com>
diff --git a/docs/getting_started/tfm_secure_boot.rst b/docs/getting_started/tfm_secure_boot.rst
index 82c1381..3b1d8b7 100644
--- a/docs/getting_started/tfm_secure_boot.rst
+++ b/docs/getting_started/tfm_secure_boot.rst
@@ -246,6 +246,8 @@
 +---------------------+-----------------+---------------+----------+----------------+--------------+
 | AN524               | Yes             | No            | No       | Yes            | No           |
 +---------------------+-----------------+---------------+----------+----------------+--------------+
+| AN547               | No              | Yes           | Yes      | Yes            | No           |
++---------------------+-----------------+---------------+----------+----------------+--------------+
 | PSoC64              | Yes             | No            | No       | No             | No           |
 +---------------------+-----------------+---------------+----------+----------------+--------------+
 | STM_DISCO_L562QE    | No              | Yes           | No       | No             | No           |