fastboot: Extend fastboot_set_reboot_flag with reboot reason

Extend fastboot_set_reboot_flag arguments with reboot reason so that
it could handle different reboot cases in future.

Signed-off-by: Roman Kovalivskyi <roman.kovalivskyi@globallogic.com>
diff --git a/board/amazon/kc1/kc1.c b/board/amazon/kc1/kc1.c
index 7d62a1d..973bc5a 100644
--- a/board/amazon/kc1/kc1.c
+++ b/board/amazon/kc1/kc1.c
@@ -8,6 +8,7 @@
 #include <config.h>
 #include <common.h>
 #include <env.h>
+#include <fastboot.h>
 #include <init.h>
 #include <linux/ctype.h>
 #include <linux/usb/musb.h>
@@ -163,8 +164,11 @@
 	omap_die_id_get_board_serial(serialnr);
 }
 
-int fastboot_set_reboot_flag(void)
+int fastboot_set_reboot_flag(enum fastboot_reboot_reason reason)
 {
+	if (reason != FASTBOOT_REBOOT_REASON_BOOTLOADER)
+		return -ENOTSUPP;
+
 	return omap_reboot_mode_store("b");
 }