Fixes extended test failure and adding tags

Fixes:
   - Changing the Force tags PNOR_BIOS_Code_Update to BIOS_Code_Update
     in test_bios_update.robot
   - Added Tag Network_Nping in extended/test_network_nping.robot
   - Added Tag Network_Nping test_lists/skip_test_extended
   - Added Tag Networkd_Ext in extended/test_netwokd_ext.robot
   - Added 'REST Power On' to boot to OS in 'eSEL Test SetUp'
     in test_esel.robot

Resolves openbmc/openbmc-test-automation#726

Change-Id: Ia9b99ae94e6ac307658ff483a4c00dd2713be35a
Signed-off-by: Sweta Potthuri <spotthur@in.ibm.com>
diff --git a/extended/test_network_nping.robot b/extended/test_network_nping.robot
index b9a81c0..071f0a8 100644
--- a/extended/test_network_nping.robot
+++ b/extended/test_network_nping.robot
@@ -8,6 +8,8 @@
 
 Suite Setup  Validate Setup
 
+Force Tags  Network_Nping
+
 *** Variables ***
 
 ${delay}             200ms