Use _pmbus_write_word_data to allow intercepting writes to
PMBUS_SMBALERT_MASK in the custom chip specific code.

This is required for MP2971/MP2973 which doesn't follow the
PMBUS specification for PMBUS_SMBALERT_MASK.
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Signed-off-by: Naresh Solanki <naresh.solanki@9elements.com>
Link: https://lore.kernel.org/r/20240130152903.3651341-1-naresh.solanki@9elements.comSigned-off-by: Guenter Roeck <linux@roeck-us.net>