bcache-tools: add is_zoned_device()

This is a wrapper of get_zone_size(), to check whether a device is
zoned device or not by checking its chunk_sectors.

Signed-off-by: Coly Li <colyli@suse.de>
diff --git a/zoned.c b/zoned.c
index 31c9136..d078286 100644
--- a/zoned.c
+++ b/zoned.c
@@ -87,3 +87,8 @@
 
 	*data_offset = _data_offset;
 }
+
+int is_zoned_device(char *devname)
+{
+	return (get_zone_size(devname) != 0);
+}
diff --git a/zoned.h b/zoned.h
index 1c5cce8..25e5c91 100644
--- a/zoned.h
+++ b/zoned.h
@@ -9,5 +9,6 @@
 #define __ZONED_H
 
 void check_data_offset_for_zoned_device(char *devname, uint64_t *data_offset);
+int is_zoned_device(char *devname);
 
 #endif