[nrf fromtree] modules: tf-m: Remove platform_ns target

The platform_ns library is no longer build with the split build anymore
so removing it.

Signed-off-by: Markus Swarowsky <[email protected]>
(cherry picked from commit 8b257c0)
Signed-off-by: Markus Swarowsky <[email protected]>

Author: mswarowsky

modules/trusted-firmware-m/nordic_nrf/CMakeLists.txt

@@ -36,14 +36,6 @@ target_include_directories(platform_s
         ${board_includes}
 )
 
-target_include_directories(platform_ns
-    PUBLIC
-        include
-        include/util
-        ${partition_includes}
-        ${board_includes}
-)
-
 if(BL2)
     target_include_directories(platform_bl2
         PUBLIC