staging: unisys: refactor visorchipset_file_init()

Fix the declaration so it is a single line. Fix CamelCase parameter
names:

MajorDev => major_dev
pControlVm_channel => controlvm_channel

Remove the unnecessary gotos and just return directly in error cases.
Fix the last error condition so it returns the result of cdev_add()
instead of always zero.

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