spl: Add a name to the SPL load-image methods

It is useful to name each method so that we can print out this name when
using the method. Currently this happens using a separate function. In
preparation for unifying this, add a name to each method.

The name is only available if we have libcommon support (i.e can use
printf()).

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/common/spl/spl_ubi.c b/common/spl/spl_ubi.c
index c03910b..24633f4 100644
--- a/common/spl/spl_ubi.c
+++ b/common/spl/spl_ubi.c
@@ -78,5 +78,5 @@
 	return ret;
 }
 /* Use priorty 0 so that Ubi will override NAND and ONENAND methods */
-SPL_LOAD_IMAGE_METHOD(0, BOOT_DEVICE_NAND, spl_ubi_load_image);
-SPL_LOAD_IMAGE_METHOD(0, BOOT_DEVICE_ONENAND, spl_ubi_load_image);
+SPL_LOAD_IMAGE_METHOD("NAND", 0, BOOT_DEVICE_NAND, spl_ubi_load_image);
+SPL_LOAD_IMAGE_METHOD("OneNAND", 0, BOOT_DEVICE_ONENAND, spl_ubi_load_image);