staging: r8188eu: remove HW_VAR_ANTENNA_DIVERSITY_SELECT from SetHwReg8188EU()

Remove the HW_VAR_ANTENNA_DIVERSITY_SELECT case from SetHwReg8188EU()
and move its functionality to rtw_cmd.c where it is actually used.
This is part of the ongoing effort to get rid of the unwanted hal
layer.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20220402092332.6627-5-straube.linux@gmail.com


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