Fix typo in "show remote traceframe-info-packet"

I noticed:

  (gdb) show remote traceframe-info-packet
  Support for the `qXfer:trace-frame-info:read' packet is auto-detected, currently unknown.
                         ^^^^^^^^^^^

The packet is actually qXfer:traceframe-info:read.

gdb/
2013-05-10  Pedro Alves  <palves@redhat.com>

	* remote.c (_initialize_remote): Fix spelling of
	qXfer:traceframe-info:read packet in packet config command.