lcd: remove CONFIG_ATMEL_LCD ifdefs from lcd_setfgcolor

Not all boards defining LCD_COLOR16 are able to set
lcd_color_fg/lcd_color_bg correctly. The issue seems to
be caused by CONFIG_ATMEL_LCD ifdefs in lcd_setfgcolor()
and lcd_setbgcolor(). Actually, the color values passed
to these functions are already correct, we don't need
to fix them. So remove ifdefs here.

Reported-by: Alessandro Rubini <rubini@unipv.it>
Signed-off-by: Anatolij Gustschin <agust@denx.de>