staging: unisys: visorbus: Remove useless initialization.

The variable ctx was allocated with kzalloc, so all the data inside is
zero, no need to reset it to 0.

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>