dp8393x: fix CAM descriptor entry index

dp8393x: fix CAM descriptor entry index

Currently when a LOAD CAM command is executed the entries are loaded into the
CAM from memory in order which is incorrect. According to the datasheet the
first entry in the CAM descriptor is the entry index which means that each
descriptor may update any single entry in the CAM rather than the Nth entry.

Decode the CAM entry index and use it store the descriptor in the appropriate
slot in the CAM. This fixes the issue where the MacOS toolbox loads a single
CAM descriptor into the final slot in order to perform a loopback test which
must succeed before the Ethernet port is enabled.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Tested-by: Finn Thain <fthain@linux-m68k.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210625065401.30170-10-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>