app/testpmd: set packet dump based on verbosity level

app/testpmd: set packet dump based on verbosity level

when changing verbosity level it will configure rx/tx callbacks to dump
packets based on the verbosity value as following:
    1- dump only received packets:
       testpmd> set verbose 1
    2- dump only sent packets:
       testpmd> set verbose 2
    3- dump sent and received packets:
       testpmd> set verbose (any number > 2)
    4- disable dump
       testpmd> set verbose 0

Signed-off-by: Raslan Darawsheh <rasland@mellanox.com>
Acked-by: Bernard Iremonger <bernard.iremonger@intel.com>