staging:iio:buffering remove unused parameter dead_offset from read_last_n in all buffer implementations.

This element has been usused by the core for quite some time.  sca3000 set it none the less
until the rewrite in the previous patch (and hence didn't work).

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