staging: r8188eu: Remove wrapper around do_div

Wrapper routine rtw_modular64() contains only a call to do_div() and
is used once in the code. Remove the wrapper.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Link: https://lore.kernel.org/r/20210803135223.12543-9-Larry.Finger@lwfinger.net


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