drivers/1wire: add PM hooks and unlink support to sht21 sensor (allowing hot-swappable I2C bus from 1-wire converter)
* drivers/1wire: add PM hook to 1wire bus
* drivers/1wire/ds28e17.c: i2c instance must be zeroed
* drivers/sht21: add unlink support
Unlike most other unlink implementations in NuttX drivers, this one
does not allow any I2C operations after unlink, making it possible to
deallocate the I2C bus.
Approved-by: Gregory Nutt <gnutt@nuttx.org>
3cf830bd67