staging:iio:kfifo remove entirely pointless code.

I really don't want to think about how this bit got
in there.  It allocates some storage - copies something
into it then frees it without making use of it.
Oops.

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>