[GFS2] Fix sign problem in quota/statfs and cleanup _host structures

This patch fixes some sign issues which were accidentally introduced
into the quota & statfs code during the endianess annotation process.
Also included is a general clean up which moves all of the _host
structures out of gfs2_ondisk.h (where they should not have been to
start with) and into the places where they are actually used (often only
one place). Also those _host structures which are not required any more
are removed entirely (which is the eventual plan for all of them).

The conversion routines from ondisk.c are also moved into the places
where they are actually used, which for almost every one, was just one
single place, so all those are now static functions. This also cleans up
the end of gfs2_ondisk.h which no longer needs the #ifdef __KERNEL__.

The net result is a reduction of about 100 lines of code, many functions
now marked static plus the bug fixes as mentioned above. For good
measure I ran the code through sparse after making these changes to
check that there are no warnings generated.

This fixes Red Hat bz #239686

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/super.h b/fs/gfs2/super.h
index e590b2d..60a870e 100644
--- a/fs/gfs2/super.h
+++ b/fs/gfs2/super.h
@@ -16,7 +16,7 @@
 
 int gfs2_check_sb(struct gfs2_sbd *sdp, struct gfs2_sb_host *sb, int silent);
 int gfs2_read_sb(struct gfs2_sbd *sdp, struct gfs2_glock *gl, int silent);
-struct page *gfs2_read_super(struct super_block *sb, sector_t sector);
+int gfs2_read_super(struct gfs2_sbd *sdp, sector_t sector);
 
 static inline unsigned int gfs2_jindex_size(struct gfs2_sbd *sdp)
 {