staging: unisys: visorbus: don't need local variable cmd

The local variable cmd was just being used to dereference a field inside
of it. Get rid of the variable and just derefernce the parameter being
passed in.

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>