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/cpu/start.c b/arch/sandbox/cpu/start.c
index 4760731..b6ff5c3 100644
--- a/arch/sandbox/cpu/start.c
+++ b/arch/sandbox/cpu/start.c
@@ -308,6 +308,16 @@
 SANDBOX_CMDLINE_OPT_SHORT(show_lcd, 'l', 0,
 			  "Show the sandbox LCD display");
 
+static int sandbox_cmdline_cb_double_lcd(struct sandbox_state *state,
+					 const char *arg)
+{
+	state->double_lcd = true;
+
+	return 0;
+}
+SANDBOX_CMDLINE_OPT_SHORT(double_lcd, 'K', 0,
+			  "Double the LCD display size in each direction");
+
 static const char *term_args[STATE_TERM_COUNT] = {
 	"raw-with-sigs",
 	"raw",