OMAP: DSS2: Change remaining DISPC functions for new omap_channel argument

The following dispc functions are also changed to incorporate channel as an argument:
	-dispc_lclk_rate()
	-dispc_pclk_rate()
	-dispc_set_pol_freq()
	-dispc_set_clock_div()
	-dispc_get_clock_div()

Signed-off-by: Sumit Semwal <sumit.semwal@ti.com>
Signed-off-by: Mukund Mittal <mmittal@ti.com>
Signed-off-by: Samreen <samreen@ti.com>
Signed-off-by: Archit Taneja <archit@ti.com>
[tomi.valkeinen@nokia.com: fixed trivial compile error]
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@nokia.com>