rbd-fuse.c: fix -Wmissing-field-initializers

Init image_name with NULL to fix:

rbd_fuse/rbd-fuse.c:57:63: warning: missing field 'image_name' initializer
 [-Wmissing-field-initializers]
 struct rbd_options rbd_options = {"/etc/ceph/ceph.conf", "rbd"};

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
rbd-fuse.c: fix indentation

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
rbd-fuse.c: remove ridiculous linebreak

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>