Display and "minor" DVFS/OPP fixes

- Support 4.3" display in the panel-generic-dpi driver
- Hard-code touchscreen size to 480x272 (temporary until there's time to implement a better solution)
- Assorted OPP/DVFS changes found during kernel panic exploration. Leaving them in for now, but they will be part of any forward porting to kernel 3.4.48 already.