boards: aithinker: update vendor name for Ai-Thinker WB2-12F board

This board is from aithinker, not BouffaloLabs, so update the vendor
info accordingly.

Signed-off-by: Benjamin Cabé <benjamin@zephyrproject.org>

Author: kartben

boards/aithinker/ai_wb2_12f/board.yml

@@ -1,6 +1,6 @@
 board:
   name: ai_wb2_12f
   full_name: Ai-Thinker WB2-12F development board
-  vendor: bflb
+  vendor: aithinker
   socs:
     - name: bl602c00q2i