Now that we have the common DSS PLL support, change HDMI to use it. This
results in quite a lot of changes, but almost all of them are trivial
name changes.

The function to program the PLL settings can be removed from hdmi_pll.c,
as the common PLL API contains the same functionality.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>