Hi Nielse,
The below script is working fine to deploy Linux VMs finally.. Thanks Nielse for all your help, time quick response..
Import-Csv "C:\Users\sg0217865\Desktop\NewVMs.csv" -UseCulture | %{
Get-OSCustomizationSpec $_.Customization | Get-OSCustomizationNicMapping | Set-OSCustomizationNicMapping -IpMode UseStaticIP -IpAddress $_.ip -SubnetMask $_.subnet -DefaultGateway $_.gw
$vm=New-VM -Name $_.Name -Template $_.Template -Host $_.Host -Datastore $_.Datastore -Confirm:$false -RunAsync -OSCustomizationSpec $_.Customization
}