Early Radeon 7000/VE chips were R100 chips, so that is my opinion on why it will continue to be hard to find a clear answer. I have the impression that changed, but it may not have.
The 10/00 entry at the top of this page confirms what I recall. Seems to indicate the Radeon was 25 million transistors.
Searching the rest of the site...
This 02/01 entry seems to confirm that the same designation (RV100) referred to a different chip at a later date.
Being bored, as I often am Saturdays
I pursued this further after the monicker RV150 for such an update part occurred to me, but the only
search result I found was out of date and wasn't very strong confirmation that this guess would be fruitful.
So, I tried a different approach...it occurred to me that I'm always saying how the ATI mobile parts are whatever chip design is convenient, and the features of the desktop 2001 Radeon VE/7000 (dual display on chip, transistors sacrificed) would fit well in a mobile chip.
Unfortunately, I ended up hitting every laptop spec page on the web, and decided that was enough.
But, if you can find the M6 transistor count, I think that would give you the right answer.