gpio-util: fix some warnings

Fix a couple of warnings:

-Werror=unused-parameter

so we can use meson's warning_level=3 and -Werror without build
failures.

Change-Id: I667598763790d5ab0090820de329b241639ae97c
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/gpio-util/main.cpp b/gpio-util/main.cpp
index 89e61f9..0cfacf4 100644
--- a/gpio-util/main.cpp
+++ b/gpio-util/main.cpp
@@ -45,7 +45,7 @@
  * @param[in] gpio - the GPIO object
  * @param[in] delayInMS - Unused in this function
  */
-void low(GPIO& gpio, unsigned int delayInMS)
+void low(GPIO& gpio, unsigned int)
 {
     gpio.set(GPIO::Value::low);
 }
@@ -56,7 +56,7 @@
  * @param[in] gpio - the GPIO object
  * @param[in] delayInMS - Unused in this function
  */
-void high(GPIO& gpio, unsigned int delayInMS)
+void high(GPIO& gpio, unsigned int)
 {
     gpio.set(GPIO::Value::high);
 }