ACPICA: Fixed possible corruption of global GPE list

Fixed a problem in acpi_ev_delete_gpe_xrupt where the global interrupt
list could be corrupted if the interrupt being removed was at
the head of the list. Reported by Linn Crosetto.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/events/evgpeblk.c b/drivers/acpi/events/evgpeblk.c
index 902c287..361ebe6 100644
--- a/drivers/acpi/events/evgpeblk.c
+++ b/drivers/acpi/events/evgpeblk.c
@@ -586,6 +586,10 @@
 	flags = acpi_os_acquire_lock(acpi_gbl_gpe_lock);
 	if (gpe_xrupt->previous) {
 		gpe_xrupt->previous->next = gpe_xrupt->next;
+	} else {
+		/* No previous, update list head */
+
+		acpi_gbl_gpe_xrupt_list_head = gpe_xrupt->next;
 	}
 
 	if (gpe_xrupt->next) {