drm/msm/dpu: make fix_core_ab_vote consistent with fix_core_ib_vote

The fix_core_ab_vote is an average bandwidth value, used for bandwidth
overrides in several cases. However there is an internal inconsistency:
fix_core_ib_vote is defined in KBps, while fix_core_ab_vote is defined
in Bps.

Fix that by changing the type of the variable to u32 and using * 1000ULL
multiplier when setting up the dpu_core_perf_params::bw_ctl value.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/636064/
Link: https://lore.kernel.org/r/20250209-dpu-perf-rework-v5-4-87e936cf3004@linaro.org