ocfs2: one function call less in ocfs2_init_slot_info() after error detection

__ocfs2_free_slot_info() was called by ocfs2_init_slot_info() even if a
call of the kzalloc() function failed.

Return from this implementation directly after corresponding
exception handling.

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>