perf test: Use header file util/debug.h

Use the header file util/debug.h instead of declaration of verbose
variable.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Link: http://lkml.kernel.org/r/20180528134817.36643-1-tmricht@linux.ibm.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>