orangefs: kill struct pvfs2_mount_sb_info_s

The only reason for that thing used to be the API of mount_nodev()
callback;  since we are calling pvfs2_fill_sb() ourselves now,
we don't have to shove everything into a single structure.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>