[GFS2] Tidy up dir code as per Christoph Hellwig's comments

1. Comment whitespace fix
2. Removed unused header files from dir.c
3. Split the gfs2_dir_get_buffer() function into two functions

Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
3 files changed