Add KTLS support in tls_wolfssl

[vladpaiu]

Summary
Add Kernel TLS support in tls_wolfssl

Details
Try to use KTLS for RX and TX ( dependent on Kernel support and loaded modules https://docs.kernel.org/networking/tls-offload.html )
If kernel support is not found, or if the cypher attempted to be used is not supported ( only AES-GCM for now ), then SSL operations will continue to be done in user-space.
IF NIC supports SSL offloading, that can also be enabled without any changes needed to the module https://docs.nvidia.com/doca/sdk/ktls-offloads/index.html

Solution
Add Kernel TLS suppor in tls_wolfssl

Easy testing with modparam("tls_wolfssl","try_use_ktls", 1)

printf 'OPTIONS sip:localhost SIP/2.0\r\nVia: SIP/2.0/TLS 127.0.0.1:5061;branch=z9hG4bK-1\r\nMax-Forwards: 70\r\nTo: <sip:localhost>\r\nFrom: <sip:tester@localhost>;tag=1\r\nCall-ID: options-1@localhost\r\nCSeq: 1 OPTIONS\r\nContact: <sip:tester@127.0.0.1:5061;transport=tls>\r\nContent-Length: 0\r\n\r\n' | openssl s_client -connect localhost:44433 -tls1_2 -servername localhost -ign_eof

Observe encryption handled in kernel-space

DBG:tls_wolfssl:_wolfssl_read: KTLS RX read 276 bytes
DBG:tls_wolfssl:_wolfssl_tls_write: KTLS write was successful (278 bytes)

Compatibility
Backwards compatible, try_use_ktls defaults to 0