Drop redundant CHIP_NAME in mainboard.c

Compose the name from Kconfig strings instead.

As the field is for debug print use only, a minor change in the output
should do no harm. The strings no longer include word "Mainboard".

Change-Id: Ifd24f408271eb5a5d1a08a317512ef00cb537ee2
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/1635
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/include/device/device.h

@@ -117,6 +117,8 @@ extern struct device	*all_devices;	/* list of all devices */
 extern struct resource	*free_resources;
 extern struct bus	*free_links;
 
+extern const char mainboard_name[];
+
 /* IGD UMA memory */
 extern uint64_t uma_memory_base;
 extern uint64_t uma_memory_size;