Defer PPIN read until BIOS enables it

On platforms with AST2600 BMC, we now boot fast enough to read the PPIN
over PECI before the BIOS has a chance to enable it (by default it is
not readable). This commit delays the RdPkgConfig until BIOS is done
with POST.

Without this change, a value of 0 is read (and 0x90 CC - but that's
ignored), which causes us to drop it.

This also removes some unnecessary phosphor namespacing.

Tested:
- Booted from AC cycle, confirmed from journal logs that cpuinfoapp
  delays an extra minute before running through getProcessorInfo. PPIN
  is now set into SerialNumber D-Bus property and shown on Redfish.

Signed-off-by: Jonathan Doman <jonathan.doman@intel.com>
Change-Id: Ie3e8c668c6b24b42ced22fd9e103d1518702d78a
diff --git a/src/speed_select.cpp b/src/speed_select.cpp
index 2c1ef6e..c320e39 100644
--- a/src/speed_select.cpp
+++ b/src/speed_select.cpp
@@ -664,7 +664,7 @@
 
     static std::string generatePath(int index)
     {
-        return phosphor::cpu_info::cpuPath + std::to_string(index);
+        return cpuPath + std::to_string(index);
     }
 };