drm/msm/mdss: Rename path references to mdp_path

The DPU1 driver needs to handle all MDPn<->DDR paths, as well as
CPU<->SLAVE_DISPLAY_CFG. The former ones share how their values are
calculated, but the latter one has static predefines spanning all SoCs.

In preparation for supporting the CPU<->SLAVE_DISPLAY_CFG path, rename
the path-related struct members to include "mdp_".

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/570163/
Link: https://lore.kernel.org/r/20231202224247.1282567-3-dmitry.baryshkov@linaro.org