Change error on FW update invalid Content-Type

Return 415 for invalid Content-Type in firmware update POST

Change-Id: I6b9cf6629c12ce191804bd0ce23bc97da9328c82
Signed-off-by: Sandeep Patil <sandeepap@ami.com>
diff --git a/redfish-core/lib/update_service.hpp b/redfish-core/lib/update_service.hpp
index 8a778f7..72ade3c 100644
--- a/redfish-core/lib/update_service.hpp
+++ b/redfish-core/lib/update_service.hpp
@@ -1122,7 +1122,8 @@
     else
     {
         BMCWEB_LOG_DEBUG("Bad content type specified:{}", contentType);
-        asyncResp->res.result(boost::beast::http::status::bad_request);
+        asyncResp->res.result(
+            boost::beast::http::status::unsupported_media_type);
     }
 }