qcacmn: Fix function return type for epping_hard_start_xmit

Fix function return type for epping_hard_start_xmit.
Currently .ndo_start_xmit callback functions returns int, but
the correct return type should be netdev_tx_t.

Change-Id: I36d3cc886bfa0fd74a264f2791f09a251baab2ef
CRs-Fixed: 2219223
1 file changed