cmd: fs: Use part_get_info_by_dev_and_name_or_num to parse partitions

This allows using dev#partlabel syntax.

Signed-off-by: Sean Anderson <sean.anderson@seco.com>
diff --git a/fs/fs.c b/fs/fs.c
index 900928c..b7936fd 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -385,8 +385,8 @@
 	}
 #endif
 
-	part = blk_get_device_part_str(ifname, dev_part_str, &fs_dev_desc,
-					&fs_partition, 1);
+	part = part_get_info_by_dev_and_name_or_num(ifname, dev_part_str, &fs_dev_desc,
+						    &fs_partition, 1);
 	if (part < 0)
 		return -1;
 
diff --git a/include/part.h b/include/part.h
index 7f78271..419c859 100644
--- a/include/part.h
+++ b/include/part.h
@@ -230,7 +230,7 @@
  * @param[in] allow_whole_dev true to allow the user to select partition 0
  *		(which means the whole device), false to require a valid
  *		partition number >= 1
- * @return 0 on success, or a negative on error
+ * @return the partition number on success, or negative errno on error
  */
 int part_get_info_by_dev_and_name_or_num(const char *dev_iface,
 					 const char *dev_part_str,
@@ -275,6 +275,16 @@
 					  struct disk_partition *info,
 					  int allow_whole_dev)
 { *dev_desc = NULL; return -1; }
+static inline int
+part_get_info_by_dev_and_name_or_num(const char *dev_iface,
+				     const char *dev_part_str,
+				     struct blk_desc **dev_desc,
+				     struct disk_partition *part_info,
+				     int allow_whole_dev)
+{
+	*dev_desc = NULL;
+	return -ENOSYS;
+}
 #endif
 
 /*