Fix logic error in gvinum's gv_set_sd_state()
With clang 4.0.0, I'm getting the following warnings:
sys/geom/vinum/geom_vinum_state.c:186:7: error: logical not is only
applied to the left hand side of this bitwise operator
[-Werror,-Wlogical-not-parentheses]
if (!flags & GV_SETSTATE_FORCE)
^ ~The logical not operator should obiously be called after masking.
Reviewed by: mav, pfg
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D9093