dfu: dfu_nand: reduce verbosity

In combination with multiple partitions in NAND, this printf() ends up
being more noise than helpful. Change it to debug() instead.

Signed-off-by: Ralph Siemsen <ralph.siemsen@linaro.org>
Acked-by: Lukasz Majewski <lukma@denx.de>

drivers/dfu/dfu_nand.c

@@ -214,7 +214,7 @@ int dfu_fill_entity_nand(struct dfu_entity *dfu, char *devstr, char *s)
 		part = simple_strtoul(s, &s, 10);
 
 		sprintf(mtd_id, "%s%d,%d", "nand", dev, part - 1);
-		printf("using id '%s'\n", mtd_id);
+		debug("using id '%s'\n", mtd_id);
 
 		mtdparts_init();