staging: rtl8723bs: remove _rtw_sd_f0_read8()

Both the _rtw_sd_f0_read8() function and the rtw_sd_f0_read8()
redefinition are used anywhere in the driver and can be removed.

Signed-off-by: Bryan Brattlof <hello@bryanbrattlof.com>
Link: https://lore.kernel.org/r/5f025724ea7149e6ff11f94352b3321833f9bcaf.1621361919.git-series.hello@bryanbrattlof.com


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