drivers: sensors: sht3xd: allow multiple instances
drivers: sensors: sht3xd: allow multiple instances

Make this driver multi-instance.

Signed-off-by: Bartosz Bilas <f2224e9ed20f1638b56e0c6dc7148d2dfd81819f@grinn-global.com>

zephyrproject-rtos/zephyr,finikorg/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,finikorg/zephyr,galak/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr