f2fs: avoid extra ++ while returning from get_node_path

In all the breaking conditions in get_node_path, 'n' is used to
track index in offset[] array, but while breaking out also, in all
paths n++ is done.
So, remove the ++ from breaking paths. Also, avoid
reset of 'level=0' in first case.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>