app/testpmd: fix L2TPv2 message type
app/testpmd: fix L2TPv2 message type

In "msg_type |= 0xc800", wider "51200" has high-order bits (0xc800)
that don't affect the narrower left-hand side.

This patch fixes coverity issue by changing the definition type of
"msg_type" from uint8_t to uint16_t.

Coverity issue: 373651
Fixes: 748530f0354e ("app/testpmd: support L2TPv2 and PPP protocol pattern")

Signed-off-by: Jie Wang <28cdc5151f9f1ff6f3675d64d2ac4944557025eb@intel.com>
Reviewed-by: Ferruh Yigit <ba8734c3c506d2e3557bd4ac8fdaccd25bdb9aa7@intel.com>

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