Revert "Corstone-310 FVP update"

This reverts commit de1a9f6e9bdd2243c4158789834ef21ee94fc31c.

Change-Id: I9cc6ba7d595a0606254bf9116517be6095eb5470
diff --git a/targets/corstone-310/CMakeLists.txt b/targets/corstone-310/CMakeLists.txt
index d943797..127570d 100644
--- a/targets/corstone-310/CMakeLists.txt
+++ b/targets/corstone-310/CMakeLists.txt
@@ -26,7 +26,7 @@
     set(CMAKE_TOOLCHAIN_FILE "${CMAKE_CURRENT_SOURCE_DIR}/../../cmake/toolchain/armclang.cmake")
 endif()
 
-set(ETHOSU_TARGET_NPU_CONFIG "ethos-u65-256" CACHE STRING "NPU configuration")
+set(ETHOSU_TARGET_NPU_CONFIG "ethos-u55-256" CACHE STRING "NPU configuration")
 set(ETHOSU_TARGET_NPU_COUNT 1 CACHE INTERNAL "Number of NPUs")
 set(ETHOSU_TARGET_NPU_TA_COUNT 0 CACHE INTERNAL "Number of timing adapters per NPU")