Additional limits on hole reporting

Holding the zp->z_rangelock as a RL_READER over the range
0-UINT64_MAX is sufficient to prevent the dnode from being
re-dirtied by concurrent writers. To avoid potentially
looping multiple times for external caller which do not
take the rangelock holes are not reported after the first
sync. While not optimal this is always functionally correct.

This change adds the missing rangelock calls on FreeBSD to
zvol_cdev_ioctl().

Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #14512
Closes #14641