I don’t know of an official escape syntax for shortcodes and there likely isn’t one.
When wordpress parses for shortcodes it looks for [ and ]. If you want to use square brackets within a shortcode, using the respective html ASCII entities escapes them.
I.e. replacing [ by [ and ] by ]. WordPress will not recognize ] as the end of the shortcode.
Whether that serves your purpose obviously depends on whether it gets converted to ] before being passed to the Google Maps API or whether the API handles it as expected. I have no experience with that, so can’t say.