ad7606: add handling in to_volts() method for 'int' and 'list'

At least the 'raw' channel attribute returns int.
So,  'ad7606.to_volts(0, channel0.raw)' won't work with checking for numpy
types.

Signed-off-by: Alexandru Ardelean <aardelean@baylibre.com>

adi/ad7606.py

@@ -129,6 +129,12 @@ def to_volts(self, index, val):
         """Converts raw value to SI"""
         _scale = self.channel[index].scale
 
+        if isinstance(val, int):
+            return val * _scale
+
+        if isinstance(val, list):
+            return [x * _scale for x in val]
+
         # ADC7606C-18 will return int32 samples from the driver
         if isinstance(val, np.int32):
             return val * _scale