test: drivers: gpio: turn off rand generator.

Generator was enabled some time ago to use sys_rand32_get() however this
function is no longer in use.

Signed-off-by: Bartlomiej Buczek <bartlomiej.buczek@nordicsemi.no>

Author: nordic-babu

tests/drivers/gpio/gpio_basic_api/prj.conf

@@ -1,6 +1,4 @@
 CONFIG_GPIO=y
 CONFIG_GPIO_GET_CONFIG=y
 CONFIG_ZTEST=y
-CONFIG_ENTROPY_GENERATOR=y
-CONFIG_TEST_RANDOM_GENERATOR=y
 #CONFIG_TEST_USERSPACE=y