ocfs2: less function calls in ocfs2_figure_merge_contig_type() after error detection

ocfs2_free_path() was called in some cases by
ocfs2_figure_merge_contig_type() during error handling even if the passed
variables "left_path" and "right_path" contained still a null pointer.

Corresponding implementation details could be improved by adjustments for
jump labels according to the current Linux coding style convention.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>