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>
diff --git a/drivers/leds/leds-hp-disk.c b/drivers/leds/leds-hp-disk.c
index 53a25b1..74645ab 100644
--- a/drivers/leds/leds-hp-disk.c
+++ b/drivers/leds/leds-hp-disk.c
@@ -49,7 +49,7 @@
 
 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 };