Update Brio 83xx KBC p1 handler information

This is probably closer to how it's supposed to be.

I think I had some freak accident happen while testing and hard disk
accesses were broken somehow, but things seem to be working fine now?

src/machine/machine_table.c

@@ -18273,7 +18273,7 @@ const machine_t machines[] = {
         .type              = MACHINE_TYPE_SLOT1,
         .chipset           = MACHINE_CHIPSET_INTEL_440EX,
         .init              = machine_at_brio83xx_init,
-        .p1_handler        = NULL,
+        .p1_handler        = machine_generic_p1_handler,
         .gpio_handler      = NULL,
         .available_flag    = MACHINE_AVAILABLE,
         .gpio_acpi_handler = NULL,