radeonfb: use PCI device id in hex for name string

Additionally provide PCI device id in character format if possible.  (The
printable characters were commonly used to identify the cards.)

Signed-off-by: Andreas Herrmann <aherrman@arcor.de>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>