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/drivers/fastboot/fb_common.c b/drivers/fastboot/fb_common.c
index c3735a4..736ce1c 100644
--- a/drivers/fastboot/fb_common.c
+++ b/drivers/fastboot/fb_common.c
@@ -88,7 +88,7 @@
  * which sets whatever flag your board specific Android bootloader flow
  * requires in order to re-enter the bootloader.
  */
-int __weak fastboot_set_reboot_flag(void)
+int __weak fastboot_set_reboot_flag(enum fastboot_reboot_reason reason)
 {
 	return -ENOSYS;
 }