mb/amd: Update pademelon to eval board

While pademelon may be a desktop board, it's not available for purchase,
which means it should be presented here as an eval board.

Signed-off-by: Martin Roth <gaumless@gmail.com>
Change-Id: I5038935bb6f2ba530ea6e16ac84c1746efec8e48
Reviewed-on: https://review.coreboot.org/c/coreboot/+/71580
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

src/mainboard/amd/pademelon/board_info.txt

@@ -1,6 +1,6 @@
 Vendor name: AMD
 Board name: Pademelon
-Category: desktop
+Category: eval
 ROM package: SOIC-8
 ROM protocol: SPI
 ROM socketed: n