sysbuild: cmake: Fix ExternalZephyrProject_Add() revision handling

Fixes an issue with HWMv2 boards whereby the specified board
revision was not applied at the correct place, which would cause
the target image to fail configuration

Fixes zephyrproject-rtos#79208

Signed-off-by: Jamie McCrae <jamie.mccrae@nordicsemi.no>

share/sysbuild/cmake/modules/sysbuild_extensions.cmake

@@ -398,7 +398,22 @@ function(ExternalZephyrProject_Add)
     # unless <image>_BOARD is defined.
     if(DEFINED ZBUILD_BOARD_REVISION)
       # Use provided board revision
-      set_target_properties(${ZBUILD_APPLICATION} PROPERTIES BOARD ${ZBUILD_BOARD}@${ZBUILD_BOARD_REVISION})
+      if(ZBUILD_BOARD MATCHES "/")
+        # HWMv2 requires adding version to the board, split elements up, attach version, then
+        # reassemble into a complete string
+        string(REPLACE "/" ";" split_board_qualifiers "${ZBUILD_BOARD}")
+        list(GET split_board_qualifiers 0 target_board)
+        set(target_board ${target_board}@${ZBUILD_BOARD_REVISION})
+        list(REMOVE_AT split_board_qualifiers 0)
+        list(PREPEND split_board_qualifiers ${target_board})
+        string(REPLACE ";" "/" board_qualifiers "${split_board_qualifiers}")
+        set_target_properties(${ZBUILD_APPLICATION} PROPERTIES BOARD ${board_qualifiers})
+        set(split_board_qualifiers)
+        set(board_qualifiers)
+      else()
+        # Legacy HWMv1 support, version goes at end
+        set_target_properties(${ZBUILD_APPLICATION} PROPERTIES BOARD ${ZBUILD_BOARD}@${ZBUILD_BOARD_REVISION})
+      endif()
     else()
       set_target_properties(${ZBUILD_APPLICATION} PROPERTIES BOARD ${ZBUILD_BOARD})
     endif()