msm: emac: fix timestamping sync

Reset the RX/TX timestamp FIFO to avoid the
timestamping out of sync.

Change-Id: I8d117944671da3886262a78206e45161c1d3760f
Acked-by: Jie Luo <jluo@qti.qualcomm.com>
Signed-off-by: Gilad Avidov <gavidov@codeaurora.org>