staging: r8188eu: remove Firmware* from struct hal_data_8188e

staging: r8188eu: remove Firmware* from struct hal_data_8188e

The fields FirmwareVersion, FirmwareSubVersion and FirmwareSignature
of struct hal_data_8188e are only used in the function
rtl8188e_FirmwareDownload(). Use local variables in that function and
remove the fields from struct hal_data_8188e. FirmwareVersionRev is
not used at all, remove it as well.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20220107103620.15648-2-straube.linux@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>