jffs2: fix use of uninitialized variable

jffs2: fix use of uninitialized variable

[ Upstream commit 3ba44ee966bc3c41dd8a944f963466c8fcc60dc8 ]

When building the kernel with -Wmaybe-uninitialized, the compiler
reports this warning:

In function 'jffs2_mark_erased_block',
    inlined from 'jffs2_erase_pending_blocks' at fs/jffs2/erase.c:116:4:
fs/jffs2/erase.c:474:9: warning: 'bad_offset' may be used uninitialized [-Wmaybe-uninitialized]
  474 |         jffs2_erase_failed(c, jeb, bad_offset);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fs/jffs2/erase.c: In function 'jffs2_erase_pending_blocks':
fs/jffs2/erase.c:402:18: note: 'bad_offset' was declared here
  402 |         uint32_t bad_offset;
      |                  ^~~~~~~~~~

When mtd->point() is used, jffs2_erase_pending_blocks can return -EIO
without initializing bad_offset, which is later used at the filebad
label in jffs2_mark_erased_block.
Fix it by initializing this variable.

Fixes: 8a0f572397ca ("[JFFS2] Return values of jffs2_block_check_erase error paths")
Signed-off-by: Qingfang Deng <qingfang.deng@siflower.com.cn>
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Sasha Levin <sashal@kernel.org>