leds-hp-disk: fix build warning

drivers/leds/leds-hp-disk.c:59: warning: passing argument 4 of ‘acpi_evaluate_integer’ from incompatible pointer type
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/leds/leds-hp-disk.c

@@ -49,7 +49,7 @@ static struct acpi_hpled adev;
 
 static acpi_status hpled_acpi_write(acpi_handle handle, int reg)
 {
-	unsigned long ret; /* Not used when writing */
+	unsigned long long ret; /* Not used when writing */
 	union acpi_object in_obj[1];
 	struct acpi_object_list args = { 1, in_obj };