ipmi: constify SSIF ACPI device ids

Constify the ACPI device ID array, it doesn't need to be writable at
runtime.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>

drivers/char/ipmi/ipmi_ssif.c

@@ -1787,7 +1787,7 @@ skip_addr:
 }
 
 #ifdef CONFIG_ACPI
-static struct acpi_device_id ssif_acpi_match[] = {
+static const struct acpi_device_id ssif_acpi_match[] = {
 	{ "IPI0001", 0 },
 	{ },
 };