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

The `insn_read` handler for the EEPROM subdevice on E-series boards
(`ni_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 number corresponds to a single EEPROM address.)
Since we do not expect the EEPROM data at a particular address to change
between readings, let's just read it once and copy the value `insn->n`
times.

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

@@ -4507,9 +4507,15 @@ static int ni_eeprom_insn_read(struct comedi_device *dev,
 			       struct comedi_insn *insn,
 			       unsigned int *data)
 {
-	data[0] = ni_read_eeprom(dev, CR_CHAN(insn->chanspec));
+	unsigned int val;
+	unsigned int i;
 
-	return 1;
+	if (insn->n) {
+		val = ni_read_eeprom(dev, CR_CHAN(insn->chanspec));
+		for (i = 0; i < insn->n; i++)
+			data[i] = val;
+	}
+	return insn->n;
 }
 
 static int ni_m_series_eeprom_insn_read(struct comedi_device *dev,