az vm create (Accelerated Networking not enabled for RHEL image)

**Bug**
When using CLI commands to create a virtual machine using various RHEL images, results in accelerated networking turned off unless explicitly setting it to true via: --accelerated-networking true

**To Reproduce**
`az vm create -n -g --zone --ppg --subnet --admin-username --image RedHat:RHEL:7-LVM --size Standard_E48ds_v4 --generate-ssh-keys --boot-diagnostics-storage `

**Expected behavior**
Accelerated networking should be turned on by default. When creating manually in the portal, it is defaulted to true.

**Environment summary**
azure-cli 2.16.0 *
core 2.16.0 *
telemetry 1.0.6
Python (Linux) 3.6.10 (default, Dec 4 2020, 12:36:15)
[GCC 7.5.0]
Ubuntu 18.04.5 LTS

**Additional context**
When switching the image to Canonical:UbuntuServer:18.04-LTS, the VM comes up with accelerated networking enabled.