drm/msm/mdss: rename ubwc_version to ubwc_enc_version

Rename the ubwc_version field to ubwc_enc_version, it denotes the
version of the UBWC encoder, not the "UBWC version".

Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/550051/
Link: https://lore.kernel.org/r/20230728213320.97309-3-dmitry.baryshkov@linaro.org