sw/vec: Add model_output_header to linker files

This allows us to place the output header struct in the right place.

Change-Id: If83a76bce86555336c2f8367a1c2530cb4b28ed1
diff --git a/springbok/springbok.ld b/springbok/springbok.ld
index df28ba8..7a80efb 100644
--- a/springbok/springbok.ld
+++ b/springbok/springbok.ld
@@ -78,8 +78,7 @@
                 . = ALIGN(64);
                 _smodel_output = .;
                 _ret = .;
-                /* Reserve 12 bytes for return information. */
-                . = . + 12;
+                *(.model_output_header*)
                 *(.model_output*)
                 _emodel_output = .;
         } > MODEL_OUTPUT
diff --git a/springbok/springbok_no_wmmu.ld b/springbok/springbok_no_wmmu.ld
index 389c616..f7bfbd5 100644
--- a/springbok/springbok_no_wmmu.ld
+++ b/springbok/springbok_no_wmmu.ld
@@ -74,8 +74,7 @@
                 . = ALIGN(64);
                 _smodel_output = .;
                 _ret = .;
-                /* Reserve 12 bytes for return information. */
-                . = . + 12;
+                *(.model_output_header*)
                 *(.model_output*)
                 _emodel_output = .;
         } > TCM