Merge miscellaneous omapdss changes

Most important changes:

* Remove OMAP4 HDMI gpio handling from board files
* Add vdda_hdmi_dac supply for HDMI to twl-common.c
* Calculate DSI clocks dynamically
* Remove DSS clock dividers from 4430sdp board file
* vram.c no longer uses OMAP's sDMA to clear the memory
* Fifomerge has been reverted
* Swap GFX and WB fifos to avoid underflows