staging: comedi: comedi_buf: absorb comedi_write_array_to_buffer()

This function is only called by comedi_buf_write_samples(). Absorb it.

The buffer overflow was already checked so the overflow check of
comedi_buf_write_alloc() can be removed.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>