video, da8xx-fb: changes for am335x usage

to use this driver also on am335x based boards, the following
changes are made:

- struct lcd_ctrl_config lcd_cfg is now configurable
  through board code

- controller base is configurable through define
  DA8XX_LCD_CNTL_BASE. To be compatible with older
  da8xx based boards: If this define is missing, the
  DAVINCI_LCD_CNTL_BASE is used

- Determine LCD IP Version, and make the driver
  working on lcd revision register values:
  Version 1:
  0x4C100102
  Version 2:
  0x4F200800
  0x4F201000

Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Anatolij Gustschin <agust@denx.de>
Cc: Tom Rini <trini@ti.com>
Acked-by: Tom Rini <trini@ti.com>