that it can connect to switches at speeds other than 1gb.
This requires changing the reference clock speed. Since we still don't
have a general clock API that lets a SoC-independant driver manipulate its
own clocks, this change includes a weak reference to a routine named
cgem_set_ref_clk(). The default implementation is a no-op; SoC-specific
code can provide an implementation that actually changes the speed.
Submitted by: Thomas Skibo <ThomasSkibo@sbcglobal.net>