disk: part: Handle blkmap device in print_part_header()

Print out the blkmap device type when showing partition header for
a blkmap device.

Signed-off-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/disk/part.c b/disk/part.c
index 9127515..85244b0 100644
--- a/disk/part.c
+++ b/disk/part.c
@@ -336,6 +336,9 @@
 	case UCLASS_EFI_MEDIA:
 		puts("EFI");
 		break;
+	case UCLASS_BLKMAP:
+		puts("BLKMAP");
+		break;
 	default:
 		printf("UNKNOWN(%d)", desc->uclass_id);
 		break;