block: Fix comment for bdrv_co_get_block_status

It returns more information than binary, fix the comment.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
diff --git a/block.c b/block.c
index 88f6d9b..5f5b244 100644
--- a/block.c
+++ b/block.c
@@ -3877,9 +3877,9 @@
 } BdrvCoGetBlockStatusData;
 
 /*
- * Returns true iff the specified sector is present in the disk image. Drivers
- * not implementing the functionality are assumed to not support backing files,
- * hence all their sectors are reported as allocated.
+ * Returns the allocation status of the specified sectors.
+ * Drivers not implementing the functionality are assumed to not support
+ * backing files, hence all their sectors are reported as allocated.
  *
  * If 'sector_num' is beyond the end of the disk image the return value is 0
  * and 'pnum' is set to 0.