libpayload: Add a function to retrieve the rows and cols of the video console.

This is useful if you need to put some text in a particular place on the
screen, for instance in the middle.

Change-Id: I3dae6b62ca1917c5020ffa3e8115ea7e8e5c0643
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: http://review.coreboot.org/1734
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

payloads/libpayload/include/libpayload.h

@@ -194,6 +194,7 @@ void speaker_tone(u16 freq, unsigned int duration);
  */
 int video_init(void);
 int video_console_init(void);
+void video_get_rows_cols(unsigned int *rows, unsigned int *cols);
 void video_console_putchar(unsigned int ch);
 void video_console_putc(u8 row, u8 col, unsigned int ch);
 void video_console_clear(void);