haswell: use asmlinkage for assembly-called funcs

When the haswell MP/SMM code was developed it was using a coreboot
repository that did not contain the asmlinkage macro. Now that the
asmlinkage macro exists use it.

BUG=None
BRANCH=None
TEST=Built and booted.

Change-Id: I662f1b16d1777263b96a427334fff8f98a407755
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/3203
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/cpu/intel/haswell/haswell.h

@@ -22,6 +22,8 @@
 #ifndef _CPU_INTEL_HASWELL_H
 #define _CPU_INTEL_HASWELL_H
 
+#include <arch/cpu.h>
+
 /* Haswell bus clock is fixed at 100MHz */
 #define HASWELL_BCLK		100
 
@@ -148,7 +150,7 @@ void romstage_common(const struct romstage_params *params);
  *  +32: MTTR mask 1 63:32
  *  ...
  */
-void * __attribute__((regparm(0))) romstage_main(unsigned long bist);
+void * asmlinkage romstage_main(unsigned long bist);
 /* romstage_after_car() is the C function called after cache-as-ram has
  * been torn down. It is responsible for loading the ramstage. */
 void romstage_after_car(void);