staging: gpib: Fix request_system_control in gpio

staging: gpib: Fix request_system_control in gpio

The implementation of the bb_request_system_control function
confused setting controller-in-charge with becoming system-controller.

Remove setting controller-in-charge and add initialization of the
control lines for the system-controller role.

Fixes: 4cd654f84769 ("staging: gpib: Add gpio bitbang GPIB driver")
Tested-by: Dave Penkler <dpenkler@gmail.com>
Signed-off-by: Dave Penkler <dpenkler@gmail.com>
Link: https://lore.kernel.org/r/20250418173434.2892-2-dpenkler@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>