staging: rtl8188eu: remove some 5 GHz code

staging: rtl8188eu: remove some 5 GHz code

According to the TODO code valid only for 5 GHz should be removed.

- find and remove remaining code valid only for 5 GHz. Most of the obvious
  ones have been removed, but things like channel > 14 still exist.

Remove if statement that checks for channel > 14 from rtw_ieee80211.c.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20200320191305.10425-1-straube.linux@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>