Add static declarations to statisfy sparse warnings in:
drivers/staging/unisys/visorbus/visorbus_main.c
warning: symbol 'visorbus_debug' was not declared
warning: symbol 'visorbus_forcematch' was not declared
warning: symbol 'visorbus_forcenomatch' was not declared
warning: symbol 'visorbus_devicetest' was not declared
warning: symbol 'visorbus_debugref' was not declared
warning: symbol 'visorbus_bus_groups' was not declared
warning: symbol 'devmajorminor_create_file' was not declared
warning: symbol 'devmajorminor_remove_file' was not declared
warning: symbol 'devmajorminor_remove_all_files' was not declared
warning: symbol 'unregister_devmajorminor_attributes' was not declared