Don't pre-reserve resources for CPU devices when they are set.

CPUs can use shared (RF_SHAREABLE) resources for the I/O port used for
entering and exiting C states.  If this I/O port is included in an ACPI
system resource device, then this happens to still work, but if the port
wasn't part of a system resource device, only the first CPU could allocate
the I/O port and use C states since resource_list_reserve() was always
allocating the resource from nexus0 without RF_SHAREABLE.  By avoiding
the reservation, the flags from the bus_alloc_resource() in the CPU driver
(which include RF_SHAREABLE) are honored.

PR:		236513
Reported by:	stockhausen@collogia.de
Sleuthing by:	avg
Reviewed by:	avg
MFC after:	2 weeks

sys/dev/acpica/acpi.c

@@ -1352,6 +1352,14 @@ acpi_set_resource(device_t dev, device_t child, int type, int rid,
     if (type == SYS_RES_IRQ)
 	return (0);
 
+    /*
+     * Don't reserve resources for CPU devices.  Some of these
+     * resources need to be allocated as shareable, but reservations
+     * are always non-shareable.
+     */
+    if (device_get_devclass(child) == devclass_find("cpu"))
+	return (0);
+
     /*
      * Reserve the resource.
      *