fix compiler warnings

Fix a couple pedantic, format=, and unused-parameter warnings so we can
turn the warnings all the way up.

Change-Id: I7c6309e30147f54fc64ace99dc784fbd96c77c70
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/nmi_main.cpp b/nmi_main.cpp
index 3a12bce..36a0004 100644
--- a/nmi_main.cpp
+++ b/nmi_main.cpp
@@ -20,7 +20,7 @@
 
 #include <sdbusplus/bus.hpp>
 
-int main(int argc, char* argv[])
+int main(int, char*[])
 {
 
     constexpr auto BUSPATH_NMI = "/xyz/openbmc_project/control/host0/nmi";