Update istep boot shell execution command

Change-Id: I4449596e6433140375133d10aadf62c4a468a2ef
Signed-off-by: George Keishing <gkeishin@in.ibm.com>
diff --git a/data/boot_table_redfish.json b/data/boot_table_redfish.json
index 704b860..238fd4b 100644
--- a/data/boot_table_redfish.json
+++ b/data/boot_table_redfish.json
@@ -59,7 +59,7 @@
         },
         "bmc_reboot": 0,
         "method_type": "keyword",
-        "method": "BMC Execute Command  export PDBG_DTB=/var/lib/phosphor-software-manager/pnor/rw/DEVTREE;/usr/bin/istep  fork=${1}"
+        "method": "BMC Execute Command  bash -c 'export PDBG_DTB=/var/lib/phosphor-software-manager/pnor/rw/DEVTREE;/usr/bin/istep'  fork=${1}"
     },
     "Redfish Power Off": {
         "start": {