staging: r8188eu: remove interface_ps_func from hal_ops

Remove interface_ps_func from hal_ops from hal_ops and remove its
wrapper rtw_hal_intf_ps_func() and the unused rtl8188eu_ps_func().

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20210906190223.11396-9-straube.linux@gmail.com


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