mainapp: fix typo in the "type" string key

The SRCREV bump change failed.
https://gerrit.openbmc-project.xyz/c/openbmc/openbmc/+/50836

Tested:
The QEMU Robot test worked.

Signed-off-by: Nan Zhou <nanzhoumails@gmail.com>
Change-Id: Ic378ebf87c0cbaf220e413f9245d6d4c0fb7a926
diff --git a/mainapp.cpp b/mainapp.cpp
index 31c212b..971d327 100644
--- a/mainapp.cpp
+++ b/mainapp.cpp
@@ -55,7 +55,7 @@
     auto options = phosphor::certs::util::ArgumentParser(argc, argv);
 
     // Parse arguments
-    const std::string& typeStr = (options)["typeStr"];
+    const std::string& typeStr = (options)["type"];
     phosphor::certs::CertificateType type =
         phosphor::certs::stringToCertificateType(typeStr);
     if (type == phosphor::certs::CertificateType::Unsupported)