hwmon: pmbus: Fix -EIO seen on pli1209

hwmon: pmbus: Fix -EIO seen on pli1209

After doing performance optimizations the pli1209 driver failed to
probe with a probabilty of 2%. It wasn't able to read the PMBUS_OPERATION
register due to an -EIO error.

An investigation showed that the PLI1209 takes 230 usec to execute the
CLEAR_FAULTS command. During that time it's busy and NACKs all requests
on the SMBUS interface. It also NACKs reads on PMBUS_STATUS_BYTE
making it impossible to poll the BUSY flag.

Add a custom write_data function to just wait for not BUSY unconditionally
after sending a CLEAR_FAULTS command.

TEST: Verified using an I2C bus analyser that no more NACKs are seen after
      sending a CLEAR_FAULTS command.

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Signed-off-by: Naresh Solanki <Naresh.Solanki@9elements.com>
Link: https://lore.kernel.org/r/20230817092527.808631-3-Naresh.Solanki@9elements.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>