NetworkPkg/TlsDxe: clean up byte order conversion for EfiTlsCipherList
Fix the following style issues:
- "Data" is accessed through a pointer to UINT16 rather than to a pointer
to EFI_TLS_CIPHER. While technically correct, UINT16 is harder to
interpret against the UEFI spec.
- Array subscripting is written with weird *(Pointer + Offset)
expressions, rather than with Pointer[Offset].
- The byte order is converted with HTONS(), while it should be NTOHS().
Either way, use the Data1 and Data2 fields of EFI_TLS_CIPHER instead.