OMAPDSS: combine LCD related config into one func

Dispc has a bunch of functions used to configure output related
parameters:

- dispc_mgr_set_io_pad_mode
- dispc_mgr_enable_stallmode
- dispc_mgr_enable_fifohandcheck
- dispc_mgr_set_clock_div
- dispc_mgr_set_tft_data_lines
- dispc_lcd_enable_signal_polarity
- dispc_mgr_set_lcd_type_tft

These are all called together, and the configuration values are taken
from struct dss_lcd_mgr_config.

Instead of exposing those individual dispc functions, create a new one,
dispc_mgr_set_lcd_config(), which is used to configure the above
parameters from values in struct dss_lcd_mgr_config.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>