Split out ECDHE from process CKE code
Split out ECDHE from process CKE code

Continuing from the previous commits, this splits out the ECDHE code into
a separate function from the process CKE code.

Reviewed-by: Richard Levitte <5fb523282dd7956571c80524edc2dccfa0bd8234@openssl.org>

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl