Just like the active interface and writeback block in ctl_intf_cfg_v1(),
and later the rest of the blocks in followup active-CTL fixes or
reworks, multiple calls to this function should enable additional DSC
blocks instead of overwriting the blocks that are enabled.

This pattern is observed in an active-CTL scenario since DPU 5.0.0 where
for example bonded-DSI uses a single CTL to drive multiple INTFs, and
each encoder calls this function individually with the INTF (hence the
pre-existing update instead of overwrite of this bitmask) and DSC blocks
it wishes to be enabled, and expects them to be OR'd into the bitmask.

The reverse already exists in reset_intf_cfg_v1() where only specified
DSC blocks are removed out of the CTL_DSC_ACTIVE bitmask (same for all
other blocks and ACTIVE bitmasks), leaving the rest enabled.

Fixes: 77f6da90 ("drm/msm/disp/dpu1: Add DSC support in hw_ctl")
Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/589902/
Link: https://lore.kernel.org/r/20240417-drm-msm-initial-dualpipe-dsc-fixes-v1-4-78ae3ee9a697@somainline.orgSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>