hwmon: (pmbus/ibm-cffps) Use default debugfs attributes and lock function

Switch the driver to use the default debugfs attributes instead of
ones that provide the same data under different names. Use the lock
functions for the debugfs and led attributes, and simplify the input
history operation by dropping the timer and lock.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20230412161526.252294-3-eajames@linux.ibm.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Author: Eddie James