dp8393x: remove onboard PROM containing MAC address and checksum

dp8393x: remove onboard PROM containing MAC address and checksum

According to the datasheet the dp8393x chipset does not contain any NVRAM capable
of storing a MAC address or checksum. Now that both the MIPS jazz and m68k q800
boards generate the PROM region and checksum themselves, remove the generated
PROM from the dp8393x device itself.

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: <20210625065401.30170-6-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>