net/mlx5: fix eCPRI common header endianness

net/mlx5: fix eCPRI common header endianness

The input header of a RTE flow item is with network byte order. In
the host with little endian, the bit field order are the same as the
byte order.
When checking the eCPRI message type, the wrong field will be selected.
Fixing to use correct field.

Fixes: daa38a8924a0 ("net/mlx5: add flow translation of eCPRI header")
Cc: stable@dpdk.org
Signed-off-by: Bing Zhao <bingz@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>