staging: rtl8723bs: Change tabs for spaces

Change tabs for spaces when they are incorrectly used as separators.
Fix suggested by Julia Lawall.
Signed-off-by: Javier F. Arias <jarias.linux@gmail.com>
Link: https://lore.kernel.org/r/7b06c103665ab7250dded8c5dadc093228eee7b4.1571284318.git.jarias.linux@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>