am57xx: add support for cape detect functionality

This commit enables using the extension board detection mechanism on
AM57xx based platforms.

Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>

arch/arm/mach-omap2/omap5/Kconfig

@@ -36,6 +36,7 @@ config TARGET_AM57XX_EVM
 	select CMD_DDR3
 	select DRA7XX
 	select TI_I2C_BOARD_DETECT
+	select SUPPORT_EXTENSION_SCAN
 	imply DM_THERMAL
 	imply SCSI
 	imply SPL_THERMAL

board/ti/am57xx/board.c

@@ -43,6 +43,7 @@
 #include <hang.h>
 
 #include "../common/board_detect.h"
+#include "../common/cape_detect.h"
 #include "mux_data.h"
 
 #ifdef CONFIG_SUPPORT_EMMC_BOOT