gpio: virtuser: actually use the "trimmed" local variable

This variable is set with the intention of being passed to the
subsequent strcmp() but something went wrong and it was left unused. Use
it now.

Fixes: 91581c4 ("gpio: virtuser: new virtual testing driver for the GPIO API")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202407092245.BPnW2mr6-lkp@intel.com/
Link: https://lore.kernel.org/r/20240709151235.90523-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Author: Bartosz Golaszewski

drivers/gpio/gpio-virtuser.c

@@ -406,12 +406,12 @@ static ssize_t gpio_virtuser_direction_do_write(struct file *file,
 
 	trimmed = strim(buf);
 
-	if (strcmp(buf, "input") == 0) {
+	if (strcmp(trimmed, "input") == 0) {
 		dir = 1;
-	} else if (strcmp(buf, "output-high") == 0) {
+	} else if (strcmp(trimmed, "output-high") == 0) {
 		dir = 0;
 		val = 1;
-	} else if (strcmp(buf, "output-low") == 0) {
+	} else if (strcmp(trimmed, "output-low") == 0) {
 		dir = val = 0;
 	} else {
 		return -EINVAL;