No, one should rather use ampersand notation in DTS files. However, he did not answer my question about what/where exactly he got his file from. He also did not post the entire file so it is impossible to rely help him.
Nothing wrong at all. I guess, you did not read my note about ralink,gpio-base or did you?
You don't seem to having looked at my answer at all! Good luck...
As mentioned before, such DTS should never ever be used as it is NOT a proper one but rather a disassembled binary one. Modifying any such is just very very delicate.
Okay, then maybe you should start somewhere to learn about device trees in general first.
Then you likely just really don't know anything about device trees which makes what you are trying to achieve very very hard.
You mean one single LED? If so which of the 3 GPIOs you initially mentioned?
No, they are all already there in your DTS but then again as it is not a proper one it is very hard to make them work now.
Well, the datasheet won't really help you much. Remember, a proper Linux driver is trying to abstract all them nitty-gritty such details. So at the end you basically only need to know which GPIO controller instance and what particular GPIO thereof you want.
Anyway, referring to my earlier comment and looking at your DTS:
Please note that, unfortunately, device trees are not quite that generic as you might hope. Meaning, if you do not know where exactly that device tree came from chances are very low that it will be usable together with whatever Linux kernel version you might intend to use it with (unless it really came from somewhere where it got exactly used with that exact same Linux kernel version as well). For now, against best practice, lets hope it might be kinda usable.
Your DTS at line 106 and following contains them GPIO controller nodes. The first controller gpio@600 is even enabled. Those would be the GPIOs from 0 aka ralink,gpio-base to 23 (e.g. the next controller's ralink,gpio-base minus one).
Unfortunately, the next two are disabled. Likely, you would need the gpio@660 one which according to its ralink,gpio-base starts with GPIO 40. Now, I guess, you could set its status to okay and also add a free phandle (e.g. 0x15 as all the others are already used). As mentioned before, in a proper device tree one would use ampersand notation referring to labels which the device tree compiler would then replace with such hex numbers making sure they are all unique. So that node would look as follows: