[PATCH] fix rio_copy_to_card() for OLDPCI case

It replaced old rio_pcicopy().  That puppy did _not_ do readb() (unlike
rio_memcpy_toio()) and current implementation is simply broken - readb(NULL)
is never a valid thing to do.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>