pvr: fix overlapping comparison

The comparison here will always be true. This changes it so
height is only set if the type is not a 1D.

Fixes a warning with clang

Reviewed-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Frank Binns <frank.binns@imgtec.com>
Part-of: <mesa/mesa!15514>
207 jobs for pvr-overlapping