video: Move video_get_info_str() prototype to a header file

This should be defined in a header file so that arguments are checked.
Move it to video.h.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>

include/video.h

@@ -245,6 +245,17 @@ int lg4573_spi_startup(unsigned int bus, unsigned int cs,
 	unsigned int max_hz, unsigned int spi_mode);
 #endif
 
+/*
+ * video_get_info_str() - obtain a board string: type, speed, etc.
+ *
+ * This is called if CONFIG_CONSOLE_EXTRA_INFO is enabled.
+ *
+ * line_number:	location to place info string beside logo
+ * info:	buffer for info string (empty if nothing to display on this
+ * line)
+ */
+void video_get_info_str(int line_number, char *info);
+
 #endif /* CONFIG_DM_VIDEO */
 
 #endif