rapidio: delete an unnecessary variable initialisation in three functions

The local variable "rc" will be set to an appropriate value a bit later.
Thus omit the explicit initialisation at the beginning.

Link: http://lkml.kernel.org/r/ed729e8c-815c-8b56-a48f-1be579d0cc2b@users.sourceforge.net
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Acked-by: Alexandre Bounine <alexandre.bounine@idt.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>