net: cadence: Fix architecture dependencies

I was told that the Cadence macb driver is also useful on Microblaze.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mark Brown <broonie@kernel.org>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>