app/testpmd: add eCPRI in flow creation patterns

app/testpmd: add eCPRI in flow creation patterns

In order to verify offloading of eCPRI protocol via flow rules, the
command line of flow creation should support the parsing of the eCPRI
pattern.

Based on the specification, one eCPRI message will have the common
header and payload. Payload format is various based on the type field
of the common header. Fixed strings will be used instead of integer
to make the CLI easy for auto-completion.

The testpmd command line examples of flow to match eCPRI item are
listed below:
  1. flow create 0 ... pattern eth / ecpri / end actions ...
    This is to match all eCPRI messages.
  2. flow create 0 ... pattern eth / ecpri common type rtc_ctrl / end actions ...
    This is to match all eCPRI messages with the type #2 - "Real-Time
    Control Data".
  3. flow create 0 ... pattern eth / ecpri common type iq_data pc_id is [U16Int] / end actions ...
    This is to match eCPRI messages with the type #0 - "IQ Data", and
    the physical channel ID 'pc_id' of the messages is a specific
    value. Since the sequence ID is changeable, there is no need to
    match that field in the flow.
Currently, only type #0, #2 and #5 will be supported.

Since eCPRI could be over Ethernet layer (or after .1Q) and UDP
layer, it is the PMD driver's responsibility to check whether eCPRI
is supported and which protocol stack is supported. Network byte
order should be used for eCPRI header, the same as other headers.

Signed-off-by: Bing Zhao <bingz@mellanox.com>
Acked-by: Ori Kam <orika@mellanox.com>