staging: unisys: fix CamelCase global Visorchipset_platform_device

Rename the CamelCase variable:

Visorchipset_platform_device => visorchipset_platform_device

Update all references to use the corrected name.

Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>