cpu/x86/mp_init: use cb_err as mp_init_with_smm return type

Using cb_err as return type clarifies the meaning of the different
return values. This patch also adds the types.h include that provides
the definition of the cb_err enum and checks the return value of
mp_init_with_smm against the enum values instead of either checking if
it's non-zero or less than zero to handle the error case.

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: Ibcd4a9a63cc87fe176ba885ced0f00832587d492
Reviewed-on: https://review.coreboot.org/c/coreboot/+/58491
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>

src/soc/amd/cezanne/cpu.c

@@ -15,6 +15,7 @@
 #include <device/device.h>
 #include <soc/cpu.h>
 #include <soc/iomap.h>
+#include <types.h>
 
 _Static_assert(CONFIG_MAX_CPUS == 16, "Do not override MAX_CPUS. To reduce the number of "
 	"available cores, use the downcore_mode and disable_smt devicetree settings instead.");
@@ -51,7 +52,7 @@ static const struct mp_ops mp_ops = {
 void mp_init_cpus(struct bus *cpu_bus)
 {
 	/* Clear for take-off */
-	if (mp_init_with_smm(cpu_bus, &mp_ops) < 0)
+	if (mp_init_with_smm(cpu_bus, &mp_ops) != CB_SUCCESS)
 		printk(BIOS_ERR, "MP initialization failure.\n");
 
 	/* pre_mp_init made the flash not cacheable. Reset to WP for performance. */