s390/cio: Remove tracing for rchp instruction

Since commit d485235b

 "s390: assume diag308 set always works",
the kernel does not use the rchp instruction anymore. So let's
remove the tracing for it.

Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Acked-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>