Update Linux/AzFileDiagnostics.sh script to determine SMB version based on RHEL distro version

[bharathsm-ms]

https://github.com/Azure-Samples/azure-files-samples/blob/master/AzFileDiagnostics/Linux/AzFileDiagnostics.sh

RHEL 7.9(3.10 kernel version) supports SMB 3.0 version, but current script logic considers SMB3 support if kernel version is > 4.11.
Add special case for RHEL distro while determining SMB version and use distro version(and kernel version if needed) to determine SMB version.