hwmon: (ucd9000) Add debugfs attributes to provide mfr_status

Expose the gpiN_fault fields of mfr_status as individual debugfs
attributes. This provides a way for users to be easily notified of gpi
faults. Also provide the whole mfr_status register in debugfs.

Signed-off-by: Christopher Bostic <cbostic@linux.vnet.ibm.com>
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Eddie James <eajames@linux.vnet.ibm.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>