mtd/partition: fix compile warning

include/nuttx/mtd/mtd.h: In function ‘mtd_setpartitionname’:
mtd/mtd_partition.c:909:3: warning: ‘strncpy’ specified bound 16 equals destination size [-Wstringop-truncation]
  909 |   strncpy(priv->name, name, sizeof(priv->name));
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

drivers/mtd/mtd_partition.c

@@ -906,7 +906,7 @@ int mtd_setpartitionname(FAR struct mtd_dev_s *mtd, FAR const char *name)
 
   /* Allocate space for the name */
 
-  strncpy(priv->name, name, sizeof(priv->name));
+  strlcpy(priv->name, name, sizeof(priv->name));
   return OK;
 }
 #endif