When the buffer descriptor index exceeds 2, then a TX HANG condition
will result.
Signed-off-by: NTroy Tan <troy_tan@realsil.com.cn>
Signed-off-by: NLarry Finger <Larry.Finger@lwfinger.net>
Cc: Stable <stable@vger.kernel.org> [V3.18]
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>