Change threadx_demo to only build for Corstone-300

The threadx_demo is only supported for the Corstone-300 target so a
check for the target has been added to the CMake file

Change-Id: I2778a85582625239df0b46b9b0bf3abd12c5826f
Signed-off-by: Mikael Olsson <mikael.olsson@arm.com>
diff --git a/applications/threadx_demo/CMakeLists.txt b/applications/threadx_demo/CMakeLists.txt
index 41fabdd..e37b852 100644
--- a/applications/threadx_demo/CMakeLists.txt
+++ b/applications/threadx_demo/CMakeLists.txt
@@ -17,7 +17,7 @@
 #
 
 # Exclude this app if ThreadX target does not exist  or if NPU configuration is not H128
-if (NOT TARGET threadx OR NOT TARGET ethosu_core_driver OR NOT ETHOSU_TARGET_NPU_CONFIG STREQUAL "ethos-u55-128")
+if (NOT TARGET threadx OR NOT TARGET ethosu_core_driver OR NOT ETHOSU_TARGET_NPU_CONFIG STREQUAL "ethos-u55-128" OR NOT ETHOSU_TARGET STREQUAL "corstone-300")
     message("Skipping ThreadX application")
     return()
 endif()