xfs: merge xfs_lrw.c into xfs_file.c

Currently the code to implement the file operations is split over
two small files.  Merge the content of xfs_lrw.c into xfs_file.c to
have it in one place.  Note that I haven't done various cleanups
that are possible after this yet, they will follow in the next
patch.  Also the function xfs_dev_is_read_only which was in
xfs_lrw.c before really doesn't fit in here at all and was moved to
xfs_mount.c.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Alex Elder <aelder@sgi.com>

fs/xfs/Makefile

@@ -105,7 +105,6 @@ xfs-y				+= $(addprefix $(XFS_LINUX)/, \
 				   xfs_globals.o \
 				   xfs_ioctl.o \
 				   xfs_iops.o \
-				   xfs_lrw.o \
 				   xfs_super.o \
 				   xfs_sync.o \
 				   xfs_xattr.o)