I don't think ,there is any report which can help to get the serial no of AP.
Inventory( Report >Report Launch Pad> Inventory) is the ONLY report which gave the below information but NOT the serial no .
This report allows you to generate inventory-related information for controllers, access points, and MSEs managed by Prime Infrastructure. This information includes hardware type and distribution, software distribution, CDP information, and other statistics.
*** If anyone knows more deatils on this ,please share with us ***