staging: unisys: remove visorinput.c double negative comparison

This patch simply removes the double negative comparison for
test_bit since test_bit already preforms this check.

Signed-off-by: Erik Arfvidson <erik.arfvidson@unisys.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>