RE: [PATCH v2 net 3/6] net: enetc: ensure enetc_xdp_xmit() calls enetc_update_tx_ring_tail()

[Wei Fang]

> enetc_xdp_xmit() keeps track of 3 numbers:
> - num_frames: total length of passed struct xdp_frame **frames array
> - xdp_tx_frm_cnt: number of frames successfully sent
> - k: index of currently sent frame from array
> 
> With "k != xdp_tx_frm_cnt", the intention was to detect an early break
> due to an inability to send a frame, and to trigger a TX doorbell
> anyway.
> 
> However, that doesn't work because every time when the loop breaks,
> k and xdp_tx_frm_cnt are mathematically equal.

Since k is always equal to xdp_tx_frm_cnt, so we only need one of them,
there is no need to use two variables.