GFS2: Use rbm for gfs2_setbit()

GFS2: Use rbm for gfs2_setbit()

Use the rbm structure for gfs2_setbit() in order to simplify the
arguments to the function. We have to add a bool to control whether
the clone bitmap should be updated (if it exists) but otherwise it
is a more or less direct substitution.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>