The "wtpt" (media white point) tag of a display profile should be D50 regardless of what the actual white point is. To quote from the ICC spec here:http://color.org/ICC1v42_2006-05.pdf
"For displays, the values specified must be those of D50 normalized such that Y = 1,0 (i.e. 0,9642 1,0 0,8249)."
The actual white point of the display gets encoded into the "chad" chromatic adaptation matrix tag, and this is not something that you can easily reverse to see the value.
I believe there was a clarification on this issue by the ICC because early versions of the spec were open to interpretation that the actual white point of the display should be encoded into the "wtpt" tag.
If you want to find out what Photoshop is using for the white point of the display, you can always use the "Custom RGB..." trick. i.e.
1. In the Photoshop Color Settings dialog, *temporarily* select the "Monitor RGB - xxxxx" profile as your working RGB space.
2. Then select "Custom RGB..." in the list
3. The Custom RGB dialog should show the unadapted white point and chromaticities of the display.
4. Be sure to set your working RGB space back to whatever you were using previously.