staging: rtl8188eu: remove unused hal_data_8188e members

Remove some members of struct hal_data_8188e which are not used
in this driver.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20210612180019.20387-1-martin@kaiser.cx


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