If a trace event uses the %*.s notation, the trace_check_vprintf() will
fail and will warn about a bad processing of strings, because it does not
take into account the length field when processing the star (*) part.
Have it handle this case as well.
Link: https://lore.kernel.org/linux-nfs/[email protected]/
Reported-by: Chuck Lever III <[email protected]>
Fixes: 9a6944fee6 ("tracing: Add a verifier to check string pointers for trace events")
Signed-off-by: Steven Rostedt (VMware) <[email protected]>