ocfs2: Some tiny bug fixes for discontiguous block allocation.

The fixes include:
1. some endian problems.
2. we should use bit/bpc in ocfs2_block_group_grow_discontig to
   allocate clusters.
3. set num_clusters properly in __ocfs2_claim_clusters.
4. change name from ocfs2_supports_discontig_bh to
   ocfs2_supports_discontig_bg.

Signed-off-by: Tao Ma <tao.ma@oracle.com>
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index d389f27..c67003b 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -491,7 +491,7 @@
 	return 0;
 }
 
-static inline int ocfs2_supports_discontig_bh(struct ocfs2_super *osb)
+static inline int ocfs2_supports_discontig_bg(struct ocfs2_super *osb)
 {
 	if (osb->s_feature_incompat & OCFS2_FEATURE_INCOMPAT_DISCONTIG_BG)
 		return 1;