net: neterion: vxge: reduce stack usage in VXGE_COMPLETE_VPATH_TX

Fix the warning: [-Werror=-Wframe-larger-than=]

drivers/net/ethernet/neterion/vxge/vxge-main.c:
In function'VXGE_COMPLETE_VPATH_TX.isra.37':
drivers/net/ethernet/neterion/vxge/vxge-main.c:119:1:
warning: the frame size of 1056 bytes is larger than 1024 bytes

Dropping the NR_SKB_COMPLETED to 16 is appropriate that won't
have much impact on performance and functionality.

Signed-off-by: Bixuan Cui <cuibixuan@huawei.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>