ioctl/open return errors, not u.u_error; remove ubarelses (it is

ioctl/open return errors, not u.u_error; remove ubarelses (it is
now done in uba.c); add open routines to some disk drivers

SCCS-vsn: sys/vax/uba/ad.c 4.6
SCCS-vsn: sys/vax/uba/ct.c 4.11
SCCS-vsn: sys/vax/uba/dh.c 4.53
SCCS-vsn: sys/vax/uba/dmf.c 4.10
SCCS-vsn: sys/vax/uba/dn.c 4.9
SCCS-vsn: sys/vax/uba/dz.c 4.46
SCCS-vsn: sys/vax/uba/idc.c 4.7
SCCS-vsn: sys/vax/uba/lp.c 4.30
SCCS-vsn: sys/vax/uba/lpa.c 4.8
SCCS-vsn: sys/vax/uba/ps.c 4.7
SCCS-vsn: sys/vax/uba/rk.c 4.48
SCCS-vsn: sys/vax/uba/tm.c 4.56
SCCS-vsn: sys/vax/uba/ts.c 4.31
SCCS-vsn: sys/vax/uba/uba.c 4.51
SCCS-vsn: sys/vax/uba/uda.c 4.11
SCCS-vsn: sys/vax/uba/ut.c 4.20
SCCS-vsn: sys/vax/uba/vp.c 4.21