net/thunderx: disable L3 alignment padding

net/thunderx: disable L3 alignment padding

Based on the packet type(IPv4 or IPv6), the nicvf HW aligns
L3 data to the 64bit memory address.
The alignment creates a hole in mbuf(between the
end of headroom and packet data start).
The new revision of the HW provides an option to disable
the L3 alignment feature and make mbuf layout looks
more like other NICs. For better application compatibility,
disabling l3 alignment feature on the hardware revisions it supports.

Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>