cmake: fail when board identifier is applied in legacy hw model

Board is looked up without identifier string, which means a legacy
board may actually be found but later fails when board identifier is
included.

Thus test for HWMv1 and fail CMake is board identifier is provided for
board using HWMv1.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>

cmake/modules/boards.cmake

@@ -187,6 +187,13 @@ if(NOT BOARD_DIR)
   message(FATAL_ERROR "Invalid BOARD; see above.")
 endif()
 
+if(HWMv1 AND DEFINED BOARD_IDENTIFIER)
+  message(FATAL_ERROR
+          "Board '${BOARD}' does not support board identifiers, ${BOARD}${BOARD_IDENTIFIER}.\n"
+          "Please specify board without an identifier.\n"
+  )
+endif()
+
 cmake_path(IS_PREFIX ZEPHYR_BASE "${BOARD_DIR}" NORMALIZE in_zephyr_tree)
 if(NOT in_zephyr_tree)
   set(USING_OUT_OF_TREE_BOARD 1)