examples/iio_readdev.py: --samples argument selects number of bytes instead of number of samples

[jcormier]

--samples argument selects a number of bytes instead of a number of samples like the c version of the app.

It would be nice to have a working example on how to iterate through samples instead of bytes

$ python3 libiio/bindings/python/examples/iio_readdev.py -u ip:192.168.0.29 -s 2 ads1246 | hexdump
0000000 ffff                                   
0000002

$ iio_readdev -u ip:192.168.0.29 -s 2 ads1246 | hexdump
0000000 ffff 007f 0001 0000 8953 42b6 29fa 1691
0000010 ff7f 007f 8953 42b6 e236 431a 29fa 1691
0000020

libiio version:

$ python3 libiio/bindings/python/examples/iio_info.py --uri ip:192.168.0.29
IIO context created: network
Backend version: 0.21 (git tag: 48e5852
...