dt-binding: ptp_qoriq: add DPAA FMan support

This patch is to add bindings description for DPAA
FMan 1588 timer, and also remove its description in
fsl-fman dt-bindings document.

Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Acked-by: Madalin Bucur <madalin.bucur@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>