staging: rtl8723bs: remove unused code blocks conditioned by never set CONFIG_EXT_CLK

remove conditional code blocks checked by unused
CONFIG_EXT_CLK

cleaning required in TODO file:

find and remove code blocks guarded by never set CONFIG_FOO defines

Signed-off-by: Fabio Aiuto <fabioaiuto83@gmail.com>
Link: https://lore.kernel.org/r/e50627bb53a8c2d3fcb03a95d8d490e98beff03a.1615801722.git.fabioaiuto83@gmail.com


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