hwmon: (pmbus/tps53679) Fix driver info initialization in probe routine

Fix tps53679_probe() by using dynamically allocated "pmbus_driver_info"
structure instead of static. Usage of static structures causes
overwritten of the field "vrm_version", in case the system is equipped
with several tps53679 devices with the different "vrm_version".
In such case the last probed device overwrites this field for all
others.

Fixes: 61052652 ("hwmon: (pmbus) Add support for Texas Instruments tps53679 device")
Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>