drivers: sensor: examplesensor: use select in Kconfig

With the recent changes in how Kconfig options are enabled using DT
helpers, using select leads to a better/more scalable pattern. Each
driver Kconfig option is expected to select its dependencies now.

Signed-off-by: Gerard Marull-Paretas <gerard@teslabs.com>

Author: gmarull

drivers/sensor/examplesensor/Kconfig

@@ -4,6 +4,7 @@
 config EXAMPLESENSOR
 	bool "Example sensor"
 	default y
-	depends on GPIO && DT_HAS_ZEPHYR_EXAMPLESENSOR_ENABLED
+	depends on DT_HAS_ZEPHYR_EXAMPLESENSOR_ENABLED
+	select GPIO
 	help
 	  Enable example sensor