main: avoid unused variables

min/maxPositionVal are only used behind ENABLE_IPMI_SNOOP, so add that
check around their definition as well.

Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
Change-Id: Iaafb12e6ddacd04b8f2f8cfea295611faac89ee8
diff --git a/main.cpp b/main.cpp
index 461c5ed..7886b75 100644
--- a/main.cpp
+++ b/main.cpp
@@ -46,8 +46,10 @@
 
 static size_t codeSize = 1; /* Size of each POST code in bytes */
 const char* defaultHostInstances = "0";
+#ifdef ENABLE_IPMI_SNOOP
 const uint8_t minPositionVal = 0;
 const uint8_t maxPositionVal = 5;
+#endif
 
 #ifdef ENABLE_IPMI_SNOOP
 std::vector<std::unique_ptr<IpmiPostReporter>> reporters;