boot: arm: riscv: sandbox: Add a format for the booti file

Arm invented a new format for arm64 and something similar is also used
with RISC-V. Add this to the list of supported formats and provide a way
for the format to be detected on both architectures.

Update the genimg_get_format() function to support this.

Fix up switch() statements which don't currently mention this format.
Booti does not support a ramdisk, so this can be ignored.

Signed-off-by: Simon Glass <sjg@chromium.org>

boot/image-board.c

@@ -250,6 +250,9 @@ enum image_fmt_t genimg_get_format(const void *img_addr)
 	if (IS_ENABLED(CONFIG_ANDROID_BOOT_IMAGE) &&
 	    is_android_boot_image_header(img_addr))
 		return IMAGE_FORMAT_ANDROID;
+	if (IS_ENABLED(CONFIG_CMD_BOOTI) &&
+	    booti_is_valid(img_addr))
+		return IMAGE_FORMAT_BOOTI;
 
 	return IMAGE_FORMAT_INVALID;
 }
@@ -420,6 +423,8 @@ static int select_ramdisk(struct bootm_headers *images, const char *select, u8 a
 			done = true;
 		}
 		break;
+	case IMAGE_FORMAT_BOOTI:
+		break;
 	case IMAGE_FORMAT_INVALID:
 		break;
 	}