bnxt_en: add hwrm FW cmds for cfa_encap_record and decap_filter

Add routines for issuing the hwrm_cfa_encap_record_alloc/free
and hwrm_cfa_decap_filter_alloc/free FW cmds needed for
supporting vxlan encap/decap offload.

Signed-off-by: Sathya Perla <sathya.perla@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>