consumers can configure clock frequency
- Add ti_prcm_clk_set_source_freq wrapper for clk_set_source_freq
- Add am335x_clk_set_arm_disp_freq function to control pixel clock
frequency for LCD and HDMI output. Both of them are sensitive
to frequency skews and we need to get pixel clock matching requested
frequency as close to possible
really need it. That would be almost everywhere it was included. Add
it in a couple files that really do need it and were previously getting
it by accident via another header.
