[][kernel][common][eth][Fix panic issue for the RX ring debug command]

[Description]
Fix panic issue for the RX ring debug command.

Without this patch, the rx_ring command might cause a panic issue when
LRO is not enabled.

[Release-log]
N/A


Change-Id: I2039fa2cda37df3e75b024ab94665658c9d0eb2c
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/8460550
1 file changed