ocfs2: Use own splice write actor

We need to fill holes during a splice write. Provide our own splice write
actor which can call ocfs2_file_buffered_write() with a splice-specific
callback.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

diff --cc fs/ocfs2/aops.c
Simple merge

diff --cc fs/ocfs2/aops.h
Simple merge

diff --cc fs/ocfs2/file.c
Simple merge