RDMA/rxe: Fix redundant skb_put_zero

rxe_init_packet() in rxe_net.c calls skb_put_zero() to reserve space for
the payload and zero it out. All these bytes are then re-written with RoCE
headers and payload. Remove this useless extra copy.

Fixes: ecb238f6 ("IB/cxgb4: use skb_put_zero()/__skb_put_zero")
Link: https://lore.kernel.org/r/20210618045742.204195-7-rpearsonhpe@gmail.com


Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>