staging: rtl8192e: remove 5G related code

staging: rtl8192e: remove 5G related code

In previous patches we removed 5G code since the hardware that uses this
driver does not support 5G. There is still some 5G related code, remove it.
All the removed defines are unused and we can safely remove "N-5G" from the
rtllib_modes array.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/20230619155203.6039-1-straube.linux@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>