staging: unisys: visorbus: move DEVICE_ATTR_RO defs as-per conventions

The kernel convention is for DEVICE_ATTR_RO(<attr>) definitions to occur
immediately after the functions that implement the attribute behaviors.
DEVICE_ATTR_RO definitions in visorbus_main.c have been moved to comply
with this convention.

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