net/bnxt: fix headroom initialization

net/bnxt: fix headroom initialization

When allocating a new mbuf for Rx, the value of m->data_off should not
be reset to its default value (RTE_PKTMBUF_HEADROOM), instead of reusing
the previous undefined value, which could cause the packet to have a too
small or too high headroom.

Fixes: 2eb53b134aae ("net/bnxt: add initial Rx code")
Cc: stable@dpdk.org
Signed-off-by: Zijie Pan <zijie.pan@6wind.com>
Signed-off-by: Didier Pallard <didier.pallard@6wind.com>
Signed-off-by: Olivier Matz <olivier.matz@6wind.com>