device: acpi_name() should take a const struct device

There's no reason to mutate the struct device when determining
the ACPI name for a device. Adjust the function pointer
signature and the respective implementations to use const
struct device.

Change-Id: If5e1f4de36a53646616581b01f47c4e86822c42e
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/21527
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Subrata Banik <subrata.banik@intel.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

src/soc/intel/apollolake/chip.c

@@ -49,7 +49,7 @@
 static void *vbt;
 static struct region_device vbt_rdev;
 
-static const char *soc_acpi_name(struct device *dev)
+static const char *soc_acpi_name(const struct device *dev)
 {
 	if (dev->path.type == DEVICE_PATH_DOMAIN)
 		return "PCI0";