Add currX_alarm, currX_min_alarm, currX_max_alarm and currX_beep
attributes to the hwmon sysfs API.

currX_min_alarm and currX_max_alarm are already supported by the LTC4215
and LTC4245 drivers. currX_alarm is supported by the LTC4261 driver.
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>