Documentation: bindings: Add phy clock voting from eud

Add binding to support phy clock voting from eud. This is required
to avoid unclocked access to eud registers.

Change-Id: I25a5358c9044a2d147190c1653a1ac54660b038a
Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>