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_bios_update.robot b/extended/test_bios_update.robot
index 3d3e042..1b4305c 100644
--- a/extended/test_bios_update.robot
+++ b/extended/test_bios_update.robot
@@ -12,7 +12,7 @@
 
 Test Teardown           Test Bios Teardown
 
-Force Tags  PNOR_BIOS_Code_Update
+Force Tags  BIOS_Code_Update
 
 *** Variables ***