fs: jffs2: Fix inconsistent indentation in jffs2_mark_node_obsolete

Fix the indentation to ensure consistent code style and improve
readability, and to fix this warnings:
fs/jffs2/nodemgmt.c:635 jffs2_mark_node_obsolete() warn: inconsistent
indenting
fs/jffs2/nodemgmt.c:646 jffs2_mark_node_obsolete() warn: inconsistent
indenting

Signed-off-by: Suraj Sonawane <surajsonawane0215@gmail.com>
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>