coreinfo: reboot when finished

Behave as nvramcui.
Avoid a "General Protection Fault Exception" when launched by SeaBIOS on
pcengines APU1.

Change-Id: I00b1f859f76e693e8d49a38c1e02f4f49add85b7
Signed-off-by: Maxime de Roucy <maxime.deroucy@gmail.com>
Reviewed-on: http://review.coreboot.org/11731
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

payloads/coreinfo/coreinfo.c

@@ -301,6 +301,9 @@ int main(void)
 
 	loop();
 
+	/* reboot */
+	outb(0x6, 0xcf9);
+	halt();
 	return 0;
 }