nilfs2: fix gcc uninitialized-variable warnings in powerpc build

Some false positive warnings are reported for powerpc build.

The following warnings are reported in
 http://kisskb.ellerman.id.au/kisskb/buildresult/12519703/

   CC      fs/nilfs2/super.o
 fs/nilfs2/super.c: In function 'nilfs_resize_fs':
 fs/nilfs2/super.c:376:2: warning: 'blocknr' may be used uninitialized in this function [-Wuninitialized]
 fs/nilfs2/super.c:362:11: note: 'blocknr' was declared here
   CC      fs/nilfs2/recovery.o
 fs/nilfs2/recovery.c: In function 'nilfs_salvage_orphan_logs':
 fs/nilfs2/recovery.c:631:21: warning: 'sum' may be used uninitialized in this function [-Wuninitialized]
 fs/nilfs2/recovery.c:585:32: note: 'sum' was declared here
 fs/nilfs2/recovery.c: In function 'nilfs_search_super_root':
 fs/nilfs2/recovery.c:873:11: warning: 'sum' may be used uninitialized in this function [-Wuninitialized]

Another similar warning is reported in
 http://kisskb.ellerman.id.au/kisskb/buildresult/12520079/

   CC      fs/nilfs2/btree.o
 fs/nilfs2/btree.c: In function 'nilfs_btree_convert_and_insert':
 include/asm-generic/bitops/non-atomic.h:105:20: warning: 'bh' may be used uninitialized in this function [-Wuninitialized]
 fs/nilfs2/btree.c:1859:22: note: 'bh' was declared here

This cleans out these warnings by forcing the variables to be initialized.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/nilfs2/recovery.c b/fs/nilfs2/recovery.c
index ff00a0b..9b4f205 100644
--- a/fs/nilfs2/recovery.c
+++ b/fs/nilfs2/recovery.c
@@ -582,7 +582,7 @@
 				 struct nilfs_recovery_info *ri)
 {
 	struct buffer_head *bh_sum = NULL;
-	struct nilfs_segment_summary *sum;
+	struct nilfs_segment_summary *sum = NULL;
 	sector_t pseg_start;
 	sector_t seg_start, seg_end;  /* Starting/ending DBN of full segment */
 	unsigned long nsalvaged_blocks = 0;
@@ -814,7 +814,7 @@
 			    struct nilfs_recovery_info *ri)
 {
 	struct buffer_head *bh_sum = NULL;
-	struct nilfs_segment_summary *sum;
+	struct nilfs_segment_summary *sum = NULL;
 	sector_t pseg_start, pseg_end, sr_pseg_start = 0;
 	sector_t seg_start, seg_end; /* range of full segment (block number) */
 	sector_t b, end;