hwmon: (pmbus) export pmbus_wait and pmbus_update_ts

hwmon: (pmbus) export pmbus_wait and pmbus_update_ts

Export pmbus_wait() and pmbus_update_ts() so that PMBus device
drivers which perform raw I2C transfers outside the core helpers
can keep the PMBus core delay bookkeeping in sync.

Move PMBUS_OP_WRITE and PMBUS_OP_PAGE_CHANGE from pmbus_core.c to
pmbus.h so device drivers can pass the correct operation type flags
to pmbus_update_ts().

This is needed by the max31785 driver, which performs raw
i2c_transfer() calls for its 4-byte extended fan speed reads that
cannot use the standard PMBus word read path.

Signed-off-by: Sanman Pradhan <psanman@juniper.net>
Link: https://lore.kernel.org/r/20260321181052.27129-2-sanman.pradhan@hpe.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>