arm64: openeuler_defconfig: turn on Amazon ENA ethernet driver

This driver is turned on on x86_64 already. Let's turn it on for arm64
as AWS supports ENA device on their arm64 instance.
Signed-off-by: NKai Liu <kai.liu@suse.com>
Signed-off-by: NGuoqing Jiang <guoqing.jiang@suse.com>

arch/arm64/configs/openeuler_defconfig

@@ -2655,7 +2655,7 @@ CONFIG_NET_VENDOR_ALACRITECH=y
 # CONFIG_NET_VENDOR_ALTEON is not set
 # CONFIG_ALTERA_TSE is not set
 CONFIG_NET_VENDOR_AMAZON=y
-# CONFIG_ENA_ETHERNET is not set
+CONFIG_ENA_ETHERNET=m
 CONFIG_NET_VENDOR_AMD=y
 # CONFIG_AMD8111_ETH is not set
 # CONFIG_PCNET32 is not set