net/ena: fix FreeBSD build
net/ena: fix FreeBSD build

The FreeBSD define was removed from platform file when HAL was upgraded
to newer version.

In file included from drivers/net/ena/ena_ethdev.c:45:
	from drivers/net/ena/ena_ethdev.h:42:
	from drivers/net/ena/base/ena_com.h:37:
drivers/net/ena/base/ena_plat.h:48:2: error: "Invalid platform"

Fixes: 3adcba9a8987 ("net/ena: update HAL to the newer version")

Signed-off-by: Michal Krawczyk <a91dcbb4df49d8bfe0a9930d7ff911a4292ca1f5@semihalf.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk