Move setting the priority U-Boot variable to ubi

The service that sets the priority value is unique to the ubi
layout because there is only one version at a time on the
static layout.
Move the calling of the service to the ubi implementation.

Tested:
- Witherspoon: Priorities are still set.
- Romulus: The BMC.Updater app does not core dump with the
latest sdbusplus changes due to calling a non-existent service.

Change-Id: Ica1c68f00d5cb43c51ee09c5a3851613edf941d5
Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
diff --git a/activation.cpp b/activation.cpp
index 863ea56..8fac93c 100644
--- a/activation.cpp
+++ b/activation.cpp
@@ -240,14 +240,14 @@
     // Set the priority value so that the freePriority() function can order
     // the versions by priority.
     auto newPriority = softwareServer::RedundancyPriority::priority(value);
-    storeToFile(parent.versionId, value);
+    parent.parent.savePriority(parent.versionId, value);
     parent.parent.freePriority(value, parent.versionId);
     return newPriority;
 }
 
 uint8_t RedundancyPriority::sdbusPriority(uint8_t value)
 {
-    storeToFile(parent.versionId, value);
+    parent.parent.savePriority(parent.versionId, value);
     return softwareServer::RedundancyPriority::priority(value);
 }