staging: rtl8188eu: remove unused parameters from rtw_check_network_type

staging: rtl8188eu: remove unused parameters from rtw_check_network_type

Parameters 'ratelen' and 'channel' of function rtw_check_network_type are
unused, remove them. Reduces object file size by 62 bytes.

  text    data     bss     dec     hex filename
398525   12896    4688  416109   6596d drivers/staging/rtl8188eu/r8188eu.o
398463   12896    4688  416047   6592f drivers/staging/rtl8188eu/r8188eu.o

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20200113212939.9738-1-straube.linux@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>