ufs: change isrmdir type to bool or u_int as appropriate

[kib]

Summary

Use bool for isrmdir argument to
ufs_dirremove()/softdep_setup_remove()/newdirrem(), where it is used as
bool.

Use u_int for isrmdir argument to
ufs_dirrewrite()/softdep_setup_directory_change()
where it is 0/1/ino.  Without the change to unsigned, the
        if (isrmdir > 1)
test is broken on volumes with many inodes.
Use newparent instead of isrmdir for the argument name in this case.

Reviewed by:    markj
Fixes:  610319c766e941de96e52f2d28fea9f8cfc51aeb
Fixes:  98eb6f0eaa50d8bd9a6794f0a9da2eddeae5bcd8