wimax/i2400m: trace commands sent from user space on the "echo" pipe

When commands are sent from user space, trace both the command sent
and the answer received over the "echo" pipe instead of over the
"trace" pipe when command tracing is enabled. As well, when the device
sends a reports/indications, send it over the "echo" pipe.

The "trace" pipe is used by the device to send firmware traces;
gets confusing. Another named pipe makes it easier to split debug
information.

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>