micrel: changes to enable qos and timestamping in ks8851

change optimizes throughput by smoothing latency for DMA access
by tx and rx buffers, and timestamping to record the exit of
packet just before driver tries to write the data to spi interface

Change-Id: Ib58847aade2ba543a8c149d03215dcdf014f2996
Acked-by: Don Gosnell <dgosnell@qti.qualcomm.com>
Acked-by: Chaitanya Pratapa <cpratapa@qti.qualcomm.com>
Signed-off-by: Utkarsh Saxena <usaxena@codeaurora.org>