staging: comedi: ni_mio_common: use insn->n in ni_m_series_eeprom_insn_read()

The `insn_read` handler for the EEPROM subdevice on M-series boards
(`ni_m_series_eeprom_insn_read()`) currently ignores `insn->n` (the
number of samples to read) and assumes a single sample is to be read
into `data[0]`.  Fortunately, the Comedi core ensures that `data[]` has
a length of at least 16 so there is no problem with array bounds.

The usual Comedi convention for `insn_read` handlers is to read the same
channel `insn->n` times into successive elements of `data[]` so let's do
that.  (Each channel corresponds to a single EEPROM address.)  In this
case, the data value comes from a local copy of the EEPROM contents.

Also, follow the usual Comedi convention and return `insn->n` from the
handler to indicate success (although any non-negative value will do).
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/ni_mio_common.c

@@ -4524,10 +4524,12 @@ static int ni_m_series_eeprom_insn_read(struct comedi_device *dev,
 					unsigned int *data)
 {
 	struct ni_private *devpriv = dev->private;
+	unsigned int i;
 
-	data[0] = devpriv->eeprom_buffer[CR_CHAN(insn->chanspec)];
+	for (i = 0; i < insn->n; i++)
+		data[i] = devpriv->eeprom_buffer[CR_CHAN(insn->chanspec)];
 
-	return 1;
+	return insn->n;
 }
 
 static unsigned int ni_old_get_pfi_routing(struct comedi_device *dev,