tracing, mei: Remove unused trace event mei_pci_cfg_write

Commit a96c5482 ("mei: trace pci configuration space io") added the
trace event mei_pci_cfg_write but never used it. As trace events that
are defined take up space for data structures and functions created for
them, it is a waste of memory to have one defined but not used. Remove
this trace event.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>