RDMA/rxe: Fixup rxe_icrc_hdr

rxe_icrc_hdr() in rxe_icrc.c is no longer shared. This patch makes it
static and changes the parameter list to match the other routines there.

Link: https://lore.kernel.org/r/20210707040040.15434-7-rpearsonhpe@gmail.com


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