fix: Fixed conf file loading.

* Properly locate conf files for the shield dir name.

app/cmake/ZephyrBuildConfig.cmake

@@ -121,11 +121,11 @@ if(DEFINED SHIELD)
 		list(LENGTH S_PIECES S_PIECES_LEN)
 		while(NOT S_PIECES STREQUAL "")
 			list(POP_BACK S_PIECES)
-			list(JOIN S_PIECES "_" S_SUBSTR)
+			list(JOIN S_PIECES "_" s_substr)
-			if (S_SUBSTR STREQUAL ${shield_dir_name})
+			if ("%{s_substr}" STREQUAL "" OR "${s_substr}" STREQUAL ${shield_dir_name})
 				break()
 			endif()
-			list(APPEND shield_candidate_names ${S_SUBSTR})
+			list(APPEND shield_candidate_names ${s_substr})
 		endwhile()
 	endforeach()
 endif()
@@ -133,12 +133,11 @@ endif()
 if (ZMK_CONFIG)
 	if (EXISTS ${ZMK_CONFIG})
 		message(STATUS "ZMK Config directory: ${ZMK_CONFIG}")
-		list(APPEND DTS_ROOT ${ZMK_CONFIG})
 		list(PREPEND KEYMAP_DIRS "${ZMK_CONFIG}")
 
 		if (DEFINED SHIELD)
-			foreach (s ${shield_candidate_names})
+			foreach (s ${shield_candidate_names} ${SHIELD_AS_LIST})
-				if (DEFINED $SHIELD_DIR_${s})
+				if (DEFINED ${SHIELD_DIR_${s}})
 					get_filename_component(shield_dir_name ${SHIELD_DIR_${s}} NAME)
 				endif()
 				list(APPEND overlay_candidates "${ZMK_CONFIG}/${s}_${BOARD}.overlay")