Add a possibility to set PLATFORM_ARCH_TYPE with an environment variable

Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com>
Change-Id: I364335d4cec9d258354bd3f52e75f452886dc4db
diff --git a/lib/state_map.py b/lib/state_map.py
index ae64af5..7e7b504 100644
--- a/lib/state_map.py
+++ b/lib/state_map.py
@@ -22,7 +22,8 @@
 BuiltIn().import_resource("state_manager.robot")
 BuiltIn().import_resource("rest_client.robot")
 
-platform_arch_type = BuiltIn().get_variable_value("${PLATFORM_ARCH_TYPE}", default="power")
+platform_arch_type = os.environ.get('PLATFORM_ARCH_TYPE', '') or \
+    BuiltIn().get_variable_value("${PLATFORM_ARCH_TYPE}", default="power")
 
 # We will build eventually the mapping for warm, cold reset as well.
 VALID_STATES = {