libxfs: remove map from libxfs_readbufr_map

libxfs: remove map from libxfs_readbufr_map

The map passed in to libxfs_readbufr_map is used to check the buffer
matches the map. However, the repair readahead code has no map it
can use to validate the buffer it set up previously, so just get rid
of the map being passed in because it serves no useful purpose.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>