staging: r8188eu: remove rtw_update_mem_stat macro and associated flags

Remove the unused rtw_update_mem_stat macro and the associated flags
from include/osdep_service.h as this is all dead code.

Signed-off-by: Phillip Potter <phil@philpotter.co.uk>
Link: https://lore.kernel.org/r/20210818234853.208448-8-phil@philpotter.co.uk


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