staging: rtl8192e: Remove unused variable rfLSSI_Select and rfTxGainStage

Remove unused variable rfLSSI_Select and rfTxGainStage because they are
just once set and not used. Remove unused constants as well.

Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Reviewed-by: Dan Carpenter <error27@gmail.com>
Link: https://lore.kernel.org/r/48f05998f4d2fe2df88ff14860cc8615dd72734d.1678569965.git.philipp.g.hortmann@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>