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/smmrelocate.c

@@ -164,7 +164,7 @@ static int bsp_setup_msr_save_state(struct smm_relocation_params *relo_params)
 /* The relocation work is actually performed in SMM context, but the code
  * resides in the ramstage module. This occurs by trampolining from the default
  * SMRAM entry point to here. */
-static void __attribute__((cdecl))
+static void asmlinkage
 cpu_smm_do_relocation(void *arg, int cpu, const struct smm_runtime *runtime)
 {
 	msr_t mtrr_cap;