Convert CONFIG_LCD_DT_SIMPLEFB to Kconfig

This converts the following to Kconfig:
   CONFIG_LCD_DT_SIMPLEFB

This patch also renames this config to CONFIG_FDT_SIMPLEFB as the code in
common/lcd_simplefb.c support CONFIG_LCD and CONFIG_VIDEO.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Matthias Brugger <mbrugger@suse.com>
13 files changed