OMAP2, 3: DSS2: Move clocks from core driver to dss driver

All clock management is moved to dss platform driver. clk_get/put APIs use
dss device instead of core platform device.

Hwmod adaptation design requires each of the DSS HW IP to be a platform driver.
So the device name is changed from omapdss to omapdss_dss in 2420, 2430,
3xxx clock database files. Now the core driver "omapdss" only takes care
of panel registration with the custom bus.
core driver also uses the clk_enable() / clk_disable() APIs exposed by DSS for
clock management.
DSS driver would do clock management of clocks needed by DISPC, RFBI, DSI, VENC

TODO:  The clock content would be adapted to omap_hwmod in a seperate series.

Signed-off-by: Senthilvadivu Guruswamy <svadivu@ti.com>
Signed-off-by: Sumit Semwal <sumit.semwal@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>