Fixes for NVIDIA Tegra124 clocks:

Fixes for NVIDIA Tegra124 clocks:
 - EMC clock have standard peripheral clock block. Use it.
 - Implement full frequency set method for PLLD2. This PLL
   is used as HDMI pixel clock so we must be able to set it
   to wide range of frequencies, within 5% tolerance allowed
   by HDMI specification. Due to this, full state space search
   (over m, n, p fields) is necessary.

MFC after: 3 weeks