"DAH-or", with a rolled r.
I recommend checking out this YouTube video:
The user uploaded English-Valyrian subtitles. Turn them on in the video options. When it gets to the part where Daenarys says "A dragon is not a slave," at 2:46, she says "daor" at the end of that sentence.
"Zaldrizes buzdari iksos daor." = "A dragon is not a slave."