app/testpmd: fix MAC address parser for flow rule

app/testpmd: fix MAC address parser for flow rule

MAC address parsing was causing failure [1],
this patch partially reverts the commit
commit b5ddce8959b2 ("app/testpmd: use new ethernet address parser")

[1]
testpmd> flow validate 0  priority  2 ingress group 0 pattern eth dst
is 98:03:9B:5C:D9:00 / end actions queue index  0 / end
Bad arguments

Fixes: b5ddce8959b2 ("app/testpmd: use new ethernet address parser")

Reported-by: Raslan Darawsheh <rasland@mellanox.com>
Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
Tested-by: Raslan Darawsheh <rasland@mellanox.com>