staging: rtl8723bs: hal: Remove code valid only for 5GHz

As per TODO ,remove code valid only for 5 GHz(channel > 14).

Signed-off-by: Hariprasad Kelam <hariprasad.kelam@gmail.com>
Link: https://lore.kernel.org/r/20190714172451.GA6779@hari-Inspiron-1545


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