soc/intel/broadwell: Use `mp_cpu_bus_init`

This is needed to allow switching to Haswell CPU code in the future.

Change-Id: Ic642f32f9c4a269a66ac470b7a7217f20ff8bfba
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/46886
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/broadwell/cpu/cpu.c

@@ -616,10 +616,8 @@ static const struct mp_ops mp_ops = {
 	.post_mp_init = post_mp_init,
 };
 
-void broadwell_init_cpus(struct device *dev)
+void mp_init_cpus(struct bus *cpu_bus)
 {
-	struct bus *cpu_bus = dev->link_list;
-
 	if (mp_init_with_smm(cpu_bus, &mp_ops))
 		printk(BIOS_ERR, "MP initialization failure.\n");
 }

src/soc/intel/broadwell/include/soc/ramstage.h

@@ -7,7 +7,6 @@
 #include <soc/intel/broadwell/chip.h>
 
 void broadwell_init_pre_device(void *chip_info);
-void broadwell_init_cpus(struct device *dev);
 
 #if CONFIG(HAVE_REFCODE_BLOB)
 void broadwell_run_reference_code(void);

src/soc/intel/broadwell/northbridge.c

@@ -461,7 +461,7 @@ static struct device_operations pci_domain_ops = {
 static struct device_operations cpu_bus_ops = {
 	.read_resources   = noop_read_resources,
 	.set_resources    = noop_set_resources,
-	.init             = &broadwell_init_cpus,
+	.init             = mp_cpu_bus_init,
 };
 
 static void broadwell_enable(struct device *dev)