linker: move all linker headers to include/linker

Signed-off-by: Anas Nashif <anas.nashif@intel.com>
diff --git a/kernel/msg_q.c b/kernel/msg_q.c
index 94896e7..baf0e02 100644
--- a/kernel/msg_q.c
+++ b/kernel/msg_q.c
@@ -14,7 +14,7 @@
 #include <kernel_structs.h>
 #include <debug/object_tracing_common.h>
 #include <toolchain.h>
-#include <sections.h>
+#include <linker/sections.h>
 #include <string.h>
 #include <wait_q.h>
 #include <misc/dlist.h>