debug: fix output from VERIFY0 assertion

The previous version reported all the right info, but the VERIFY3 name
made a little more confusing when looking for the matching location in
the source code.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Signed-off-by: Rob N ★ <robn@despairlabs.com>
Closes #14099