drivers: gpio_nrfx: Free channel when changing mode

Fix an issue where calling gpio_pin_interrupt_configure
with edge mode and later calling it with level mode, did
not release the allocated gpiote channel.

Repeating the above sequence caused us to run out of
gpiote channels.

Signed-off-by: Markus Lassila <markus.lassila@nordicsemi.no>

Author: MarkusLassila

drivers/gpio/gpio_nrfx.c

@@ -444,6 +444,15 @@ static int gpio_nrfx_pin_interrupt_configure(const struct device *port,
 		}
 
 		trigger_config.p_in_channel = &ch;
+	} else {
+		/* If edge mode with channel was previously used and we are changing to sense or
+		 * level triggered, we must free the channel.
+		 */
+		err = nrfx_gpiote_channel_get(&cfg->gpiote, abs_pin, &ch);
+		if (err == NRFX_SUCCESS) {
+			err = nrfx_gpiote_channel_free(&cfg->gpiote, ch);
+			__ASSERT_NO_MSG(err == NRFX_SUCCESS);
+		}
 	}
 
 	err = nrfx_gpiote_input_configure(&cfg->gpiote, abs_pin, &input_pin_config);