Platform: Add FVP_SSE300_MPS2 target

Add support for FVP_SSE300_MPS2 platform

Change-Id: Ieddb5adbdc0cc47690bbe0b3dfbaf39d005d03ea
Signed-off-by: Mark Horvath <mark.horvath@arm.com>
Signed-off-by: Marton Berke <marton.berke@arm.com>
diff --git a/docs/user_guides/tfm_integration_guide.rst b/docs/user_guides/tfm_integration_guide.rst
index 3c4aa8e..d320a0e 100644
--- a/docs/user_guides/tfm_integration_guide.rst
+++ b/docs/user_guides/tfm_integration_guide.rst
@@ -22,6 +22,7 @@
 - Soft Macro Model (SMM) Cortex-M33 SSE-200 subsystem for MPS2+ (AN521)
 - Cortex-M23 IoT Kit subsystem for MPS2+ (AN519)
 - Arm SSE-123 Example Subsystem for MPS2+ (AN539)
+- Cortex-M55 SSE-300 subsystem for MPS2+ FVP
 - Musca-A test chip board (Cortex-M33 SSE-200 subsystem)
 - Musca-B1 test chip board (Cortex-M33 SSE-200 subsystem)
 - Musca-S1 test chip board (Cortex-M33 SSE-200 subsystem)