[hevce] Fixed mapping of MFX to Libva GOP params
[hevce] Fixed mapping of MFX to Libva GOP params

In case of interlace encode, mfx gop params are calculated
in pairs of fields but drivers params are in fields.
So we need to correctly calculate libva params.

Signed-off-by: Dmitry Ermilov <b906d09bf4e9d5ffa97d91f4baa9152f6d31529a@intel.com>

Intel-Media-SDK/MediaSDK,Intel-Media-SDK/MediaSDK,Intel-Media-SDK/MediaSDK,Intel-Media-SDK/MediaSDK,Intel-Media-SDK/MediaSDK