staging: rtl8187se: Removed legacy rtl8225_rf_set_chan()

Removed rtl8225_rf_set_chan() and corresponding arrays, changed its
usage to rtl8225z2_rf_set_chan()

Signed-off-by: Maxim Mikityanskiy <maxtram95@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>