rk3288: vyasa: Add falcon mode support

Add Falcon mode support in vyasa rk3288 board.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

board/amarula/vyasa-rk3288/vyasa-rk3288.c

@@ -5,3 +5,16 @@
  */
 
 #include <common.h>
+
+#ifndef CONFIG_TPL_BUILD
+#include <spl.h>
+
+int spl_start_uboot(void)
+{
+        /* break into full u-boot on 'c' */
+        if (serial_tstc() && serial_getc() == 'c')
+                return 1;
+
+        return 0;
+}
+#endif