Increase COMMS_MHU_MSG_SIZE limit for CS1000

The size of the messages between the Host and SE have increased
because the VARIABLE_INDEX_MAX_NAME_SIZE was increased from
32 to 64. The default COMMS_MHU_MSG_SIZE is 0x2100 which is no longer
sufficent because of this. It had to be increased accordingly
so the Embed Protocol can still be used even for the largest messages.

Change-Id: I11501dbe20c7ccf2f772a3db9e18149b2af50026
Signed-off-by: Bence Balogh <bence.balogh@arm.com>
diff --git a/platform/providers/arm/corstone1000/platform.cmake b/platform/providers/arm/corstone1000/platform.cmake
index 6632267..fe9349a 100644
--- a/platform/providers/arm/corstone1000/platform.cmake
+++ b/platform/providers/arm/corstone1000/platform.cmake
@@ -3,7 +3,7 @@
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
-# Platform definition for the 'fvp_base_revc-2xaem8a' virtual platform.
+# Platform definition for the Corstone-1000 platform.
 #-------------------------------------------------------------------------------
 
 set(SMM_GATEWAY_MAX_UEFI_VARIABLES 80 CACHE STRING "Maximum UEFI variable count")
@@ -13,6 +13,7 @@
 target_compile_definitions(${TGT} PRIVATE
 	SMM_VARIABLE_INDEX_STORAGE_UID=0x787
 	PLAT_RSS_COMMS_PAYLOAD_MAX_SIZE=0x2080
+	COMMS_MHU_MSG_SIZE=0x3500
 )
 
 get_property(_platform_driver_dependencies TARGET ${TGT}