sandbox: sdl: Add an option to double the screen size

On high-DPI displays U-Boot's LCD window can look very small. Add a
-K flag to expand it to make things easier to read, while still using
the existing resolution internally.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Anatolij Gustschin <agust@denx.de>
diff --git a/arch/sandbox/include/asm/sdl.h b/arch/sandbox/include/asm/sdl.h
index c45dbdd..47fc488 100644
--- a/arch/sandbox/include/asm/sdl.h
+++ b/arch/sandbox/include/asm/sdl.h
@@ -17,10 +17,13 @@
  * @height	Window height in pixels
  * @log2_bpp:	Log to base 2 of the number of bits per pixel. So a 32bpp
  *		display will pass 5, since 2*5 = 32
+ * @double_size: true to double the visible size in each direction for high-DPI
+ *		displays
  * @return 0 if OK, -ENODEV if no device, -EIO if SDL failed to initialize
  *		and -EPERM if the video failed to come up.
  */
-int sandbox_sdl_init_display(int width, int height, int log2_bpp);
+int sandbox_sdl_init_display(int width, int height, int log2_bpp,
+			     bool double_size);
 
 /**
  * sandbox_sdl_sync() - Sync current U-Boot LCD frame buffer to SDL
@@ -78,8 +81,8 @@
 int sandbox_sdl_sound_init(int rate, int channels);
 
 #else
-static inline int sandbox_sdl_init_display(int width, int height,
-					    int log2_bpp)
+static inline int sandbox_sdl_init_display(int width, int height, int log2_bpp,
+					   bool double_size)
 {
 	return -ENODEV;
 }