nb/intel/haswell: Add `mb_late_romstage_setup` function

This function is called at the end of `romstage_common`. Only one board
makes use of it, the Lenovo ThinkPad T440p. To preserve behavior, call
it after `romstage_common` has done nearly everything.

Change-Id: I35742879e737be4f383a0e36aecc6682fc9df058
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43094
Reviewed-by: Tristan Corrick <tristan@corrick.kiwi>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/northbridge/intel/haswell/haswell.h b/src/northbridge/intel/haswell/haswell.h
index fa32eca..7fb24c8 100644
--- a/src/northbridge/intel/haswell/haswell.h
+++ b/src/northbridge/intel/haswell/haswell.h
@@ -195,6 +195,7 @@
 	void (*copy_spd)(struct pei_data *peid);
 };
 void romstage_common(const struct romstage_params *params);
+void mb_late_romstage_setup(void); /* optional */
 
 void haswell_early_initialization(void);
 void haswell_late_initialization(void);