gpio: selftests: gpio-mockup-chardev GPIOHANDLE_REQUEST_OUTPUT fix

Following logic from commit: 22f6592b, GPIOHANDLE_REQUEST_OUTPUT
should handle errors same way as GPIOHANDLE_REQUEST_INPUT does, or else
the following error occurs:

gpio-mockup-chardev: gpio<gpiochip1> line<0> test flag<0x2> value<0>: No
such file or directory

despite the real result of gpio_pin_test(), gpio_debugfs_get() and
gpiotools_request_linehandle() functions.
Signed-off-by: Rafael David Tinoco <rafael.tinoco@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

tools/testing/selftests/gpio/gpio-mockup-chardev.c

@@ -225,10 +225,10 @@ int gpio_pin_test(struct gpiochip_info *cinfo, int line, int flag, int value)
 		if (flag & GPIOHANDLE_REQUEST_ACTIVE_LOW)
 			debugfs_value = !debugfs_value;
 
-		if (!(debugfs_dir == OUT && value == debugfs_value))
+		if (!(debugfs_dir == OUT && value == debugfs_value)) {
 			errno = -EINVAL;
-		ret = -errno;
-
+			ret = -errno;
+		}
 	}
 	gpiotools_release_linehandle(fd);