x86: Print DMI_BOARD_NAME as well as DMI_PRODUCT_NAME from __show_regs()

Robert Hancock observes that DMI_BOARD_NAME is often more useful
than DMI_PRODUCT_NAME, especially on standalone motherboards.
So, print both.

Signed-off-by: Andy Isaacson <adi@hexapodia.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Robert Hancock <hancockrwd@gmail.com>
Cc: Richard Zidlicky <rz@linux-m68k.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <20091208083021.GB27174@hexapodia.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>