staging: unisys: visornic: Replace symbolic perms with octal

Replace symbolic permissions S_IRUSR and S_IWUSR for their octal
counterparts

Signed-off-by: Thomas Jespersen <laumann.thomas@gmail.com>
Acked-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>