src/mb: Use system_reset()

Use already defined system_reset() function.

Change-Id: I68ff4cffa2bfab6a15299795c3e1837fc9b85806
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32379
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

src/mainboard/getac/p470/romstage.c

@@ -16,6 +16,7 @@
 
 #include <stdint.h>
 #include <arch/io.h>
+#include <cf9_reset.h>
 #include <device/pnp_ops.h>
 #include <device/pci_ops.h>
 #include <device/pci_def.h>
@@ -256,8 +257,7 @@ void mainboard_romstage_entry(unsigned long bist)
 
 	if (MCHBAR16(SSKPD) == 0xCAFE) {
 		printk(BIOS_DEBUG, "soft reset detected, rebooting properly\n");
-		outb(0x6, 0xcf9);
-		halt();
+		system_reset();
 	}
 
 	/* Perform some early chipset initialization required