staging: r8188eu: remove {read,write}_macreg

These 2 functions are unused, so they can be simply removed

Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Acked-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Link: https://lore.kernel.org/r/d591e29d77da73790c71f7a8e508a8b16fd48f65.1629789580.git.paskripkin@gmail.com


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