Previously, the LVGL example had a workaround in lv_nuttx_fbdev.c to prevent
video memory invasion. This fix properly addresses the issue by:
- Reducing total SDRAM size from 8MB to 6MB
- Moving LTDC base address to 0xC0600000
- Reserving dedicated space for video memory outside NuttX heap
This ensures proper memory separation between video buffer and system heap.
Signed-off-by: Jorge Guzman <jorge.gzm@gmail.com>