libf2fs: Fix using uninitialized variables error in get_device_info()

This issue comes from a static code scanning tool.
When c.sparse_mode is 1, stat_buf will not be initialized,
but it will be used next.
If this issue does not require modification, please ignore this commit.

Signed-off-by: zangyangyang1 <zangyangyang1@xiaomi.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
1 file changed