make getproperty a templated function

This will make it more generic so other types of properties can be read

Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
Change-Id: Icc7c040ec44d470b6b62d8b74200c7e35012e25c
diff --git a/usb/usb_manager.cpp b/usb/usb_manager.cpp
index 4a1f768..2bab2de 100644
--- a/usb/usb_manager.cpp
+++ b/usb/usb_manager.cpp
@@ -109,9 +109,9 @@
 
         try
         {
-            auto propVal =
-                utils::getProperty(bus, path.str, imageInterface, "Activation");
-            const auto& imageProp = std::get<std::string>(propVal);
+            auto imageProp = utils::getProperty<std::string>(
+                bus, path.str, imageInterface, "Activation");
+
             if (imageProp == readyPro && isUSBCodeUpdate)
             {
                 setApplyTime();