phosphor-ipmi-flash: Fix all C++ warnings

Change-Id: I89236b2dab88ca725e269bb8f5b2cbfd271e807a
Signed-off-by: Willy Tu <wltu@google.com>
diff --git a/bmc/firmware-handler/pci_handler.cpp b/bmc/firmware-handler/pci_handler.cpp
index 1b6b7ff..d74c4a4 100644
--- a/bmc/firmware-handler/pci_handler.cpp
+++ b/bmc/firmware-handler/pci_handler.cpp
@@ -107,7 +107,7 @@
     return results;
 }
 
-bool PciDataHandler::writeMeta(const std::vector<std::uint8_t>& configuration)
+bool PciDataHandler::writeMeta(const std::vector<std::uint8_t>&)
 {
     /* PCI handler doesn't require configuration write, only read. */
     return false;