staging: unisys: visorbus: Use __func__ instead of name.

The dev_err was using the hardcoded function name, as reported by
checkpatch, it should be using __func__.

Signed-off-by: David Kershner <david.kershner@unisys.com>
Reviewed-by: Tim Sell <timothy.sell@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>