staging: rtl8192e: Remove rt_hi_throughput::ChnkOp

Field was initialized and never used.
This patch also removes chnl_op enum that was only
referenced by ChnkOp init code.

Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>