ocfs2: clean up redundant function declarations

ocfs2_extend_allocation() has been deleted, clean up its declaration.
Also change the static function name from __ocfs2_extend_allocation() to
ocfs2_extend_allocation() to be consistent with the corresponding trace
events as well as comments for ocfs2_lock_allocators().

Link: http://lkml.kernel.org/r/09cf7125-6f12-e53e-20f5-e606b2c16b48@huawei.com


Fixes: 964f14a0 ("ocfs2: clean up some dead code")
Signed-off-by: Jia Guo <guojia12@huawei.com>
Acked-by: Joseph Qi <jiangqi903@gmail.com>
Reviewed-by: Jun Piao <piaojun@huawei.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <ge.changwei@h3c.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>