HDMI and USB are totally different technologies so you can't simply 'connect' one to the other, especially on a TV where configuration options are limited.
Looking at the Bose system it appears that their speakers use Bluetooth so if your TV has Bluetooth connectivity on it you may just be able to do a scan, pick up the speakers and select them as an audio output device.
Hmmm reading more into this is seems like the implementation of Bluetooth on Sony TV's is pretty poor. I have an LG TV and it works great but that doesn't help you.
If pairing doesn't work the other option is to take the Audio (left/Right) out from your TV and connect to something like this which will convert it to Bluetooth that can be received by your speakers.
There are many on the market and I haven't used one to recommend and it would need to be compatible with the Bose Bluetooth implementation.