phal: Added extensions/phal folder

Added phal specific folder to keep all phal feature
based function in common place

Moved phal error specific source files to  extensions/phal

Tested: build verified.

Signed-off-by: Jayanth Othayoth <ojayanth@in.ibm.com>
Change-Id: Iabae2689444f355008802950a293e7c69cb19553
diff --git a/meson.build b/meson.build
index 0913477..803a6fd 100644
--- a/meson.build
+++ b/meson.build
@@ -67,8 +67,8 @@
         'procedures/phal/proc_pre_poweroff.cpp',
         'procedures/phal/common_utils.cpp',
         'procedures/phal/check_host_running.cpp',
-        'phalerror/create_pel.cpp',
-        'phalerror/phal_error.cpp',
+        'extensions/phal/create_pel.cpp',
+        'extensions/phal/phal_error.cpp',
     ]
     extra_dependencies += [
         dependency('libdt-api'),