Fix issue with skipping AC devices in CCM15Device.py

[kangyue92]

I tried to switch to the home assistant integration "ccm15", but found no entity on my device. So I did some debug, and found that my CCM15 status.xml is not starting from a0. Here is the example response.

curl /status.xml

<?xml version="1.0" encoding="gb2312"?>
<response>
<a0>-</a0>
<a1>801000b0c00020,</a1>
<a2>801000b0b00021,</a2>
<a3>801000b0c00021,</a3>
<a4>801000b0c00020,</a4>
<a5>801000b0c00020,</a5>
<a6>-</a6>
<a7>-</a7>
<a8>-</a8>
<a9>-</a9>
<a10>-</a10>
...