hwmon: pmbus: Use devm_krealloc_array

Now that it exists, use it instead of doing the multiplication manually.

Acked-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: James Clark <james.clark@arm.com>
Link: https://lore.kernel.org/r/20230509094942.396150-3-james.clark@arm.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>