drm/msm/mdss: define bitfields for the UBWC_STATIC register

Rather than hand-coding UBWC_STATIC value calculation, define
corresponding bitfields and use them to setup the register value.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/626372/
Link: https://lore.kernel.org/r/20241127-msm-mdss-ubwc-v3-1-9782a7c2b023@linaro.org