Fix field mode test case bugs

- Fix a bug where robot does not give time for /usr/local/share
  to unmount
- Fix a bug where robot assigns None to the expected value in
  Write Attribute

Resolves openbmc/openbmc-test-automation#1107

Change-Id: I28e027daf2ec598b16e3e7b40e61551d9fdae3da
Signed-off-by: Charles Paul Hofer <Charles.Hofer@ibm.com>
diff --git a/extended/code_update/test_field_mode.robot b/extended/code_update/test_field_mode.robot
index 6bba58f..e3efce4 100644
--- a/extended/code_update/test_field_mode.robot
+++ b/extended/code_update/test_field_mode.robot
@@ -37,6 +37,7 @@
 
     ${args}=  Create Dictionary  data=${1}
     Write Attribute  ${SOFTWARE_VERSION_URI}  FieldModeEnabled  data=${args}
+    Sleep  5s
     BMC Execute Command  [ ! -d "/usr/local/share" ]