PHAL: Add service dependency to DEVTREE creation

Start the services that require DEVTREE after the
openpower-update-bios-attr-table.service since that's the one that
sets up the DEVTREE symlink. Also update the path to DEVTREE to the one
defined by the meson options.

Tested: Verified phal started after the bios attr service file, powered
on, and issued reboot at power on without any errors. Verified service
files had devtree path of:
Environment="PDBG_DTB=/media/hostfw/running/DEVTREE"

Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
Change-Id: If41f86b287b70c48d17c6f4b2af9aa0adfb81488
diff --git a/extensions/phal/pdbg_utils.cpp b/extensions/phal/pdbg_utils.cpp
index 8eadd3c..7dfc5cb 100644
--- a/extensions/phal/pdbg_utils.cpp
+++ b/extensions/phal/pdbg_utils.cpp
@@ -3,6 +3,8 @@
 #include <libpdbg.h>
 }
 
+#include "config.h"
+
 #include "extensions/phal/pdbg_utils.hpp"
 #include "extensions/phal/phal_error.hpp"
 
@@ -125,10 +127,7 @@
 void setDevtreeEnv()
 {
     // PDBG_DTB environment variable set to CEC device tree path
-    static constexpr auto PDBG_DTB_PATH =
-        "/var/lib/phosphor-software-manager/pnor/rw/DEVTREE";
-
-    if (setenv("PDBG_DTB", PDBG_DTB_PATH, 1))
+    if (setenv("PDBG_DTB", CEC_DEVTREE_RW_PATH, 1))
     {
         log<level::ERR>(
             fmt::format("Failed to set PDBG_DTB: ({})", strerror(errno))