drivers/firmware: const-ify DMI API and internals

Three main sets of changes:

1) dmi_get_system_info() return value should have been marked const,
   since callers should not be changing that data.

2) const-ify DMI internals, since DMI firmware tables should,
   whenever possible, be marked const to ensure we never ever write to
   that data area.

3) const-ify DMI API, to enable marking tables const where possible
   in low-level drivers.

And if we're really lucky, this might enable some additional
optimizations on the part of the compiler.

The bulk of the changes are #2 and #3, which are interrelated.  #1 could
have been a separate patch, but it was so small compared to the others,
it was easier to roll it into this changeset.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/hwmon/abituguru.c b/drivers/hwmon/abituguru.c
index d575ee9..2317f4b 100644
--- a/drivers/hwmon/abituguru.c
+++ b/drivers/hwmon/abituguru.c
@@ -1449,7 +1449,7 @@
 	struct resource res = { .flags = IORESOURCE_IO };
 
 #ifdef CONFIG_DMI
-	char *board_vendor = dmi_get_system_info(DMI_BOARD_VENDOR);
+	const char *board_vendor = dmi_get_system_info(DMI_BOARD_VENDOR);
 
 	/* safety check, refuse to load on non Abit motherboards */
 	if (!force && (!board_vendor ||
diff --git a/drivers/hwmon/applesmc.c b/drivers/hwmon/applesmc.c
index 941729a..56213b7 100644
--- a/drivers/hwmon/applesmc.c
+++ b/drivers/hwmon/applesmc.c
@@ -1071,7 +1071,7 @@
 /*
  * applesmc_dmi_match - found a match.  return one, short-circuiting the hunt.
  */
-static int applesmc_dmi_match(struct dmi_system_id *id)
+static int applesmc_dmi_match(const struct dmi_system_id *id)
 {
 	int i = 0;
 	struct dmi_match_data* dmi_data = id->driver_data;
diff --git a/drivers/hwmon/hdaps.c b/drivers/hwmon/hdaps.c
index e0cf5e6..a7c6d40 100644
--- a/drivers/hwmon/hdaps.c
+++ b/drivers/hwmon/hdaps.c
@@ -480,14 +480,14 @@
 /* Module stuff */
 
 /* hdaps_dmi_match - found a match.  return one, short-circuiting the hunt. */
-static int __init hdaps_dmi_match(struct dmi_system_id *id)
+static int __init hdaps_dmi_match(const struct dmi_system_id *id)
 {
 	printk(KERN_INFO "hdaps: %s detected.\n", id->ident);
 	return 1;
 }
 
 /* hdaps_dmi_match_invert - found an inverted match. */
-static int __init hdaps_dmi_match_invert(struct dmi_system_id *id)
+static int __init hdaps_dmi_match_invert(const struct dmi_system_id *id)
 {
 	hdaps_invert = 1;
 	printk(KERN_INFO "hdaps: inverting axis readings.\n");