OMAPDSS: DSI: Pass dsi platform device wherever possible

Many of the DSI functions receive the connected panel's omap_dss_device pointer
as an argument. The platform device pointer is then derived via omap_dss_device
pointers.

Most of these functions don't really require omap_dss_device pointer anymore
since we now keep copies of parameters in the driver data which were previously
available only via omap_dss_device. Replace the arguments with platform device
pointers for such functions.
Signed-off-by: Archit Taneja <archit@ti.com>