drm/msm/dpu: add writeback support for sc7180

Add writeback support for sc7180 devices. This has been
validated on sc7180 chromebook using IGT writeback test
suite.

localhost /usr/local/libexec/igt-gpu-tools # ./kms_writeback
Starting subtest: writeback-pixel-formats
Subtest writeback-pixel-formats: SUCCESS (0.001s)
Starting subtest: writeback-invalid-parameters
Subtest writeback-invalid-parameters: SUCCESS (0.004s)
Starting subtest: writeback-fb-id
Subtest writeback-fb-id: SUCCESS (0.009s)
Starting subtest: writeback-check-output
Subtest writeback-check-output: SUCCESS (0.203s)

Adding this will increase IGT coverage on chromebooks and also
allow using writeback functionality for other use-cases as
necessary.
Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/485787/
Link: https://lore.kernel.org/r/20220510235439.31916-1-quic_abhinavk@quicinc.comSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.c

@@ -1803,6 +1803,8 @@ static void sc7180_cfg_init(struct dpu_mdss_cfg *dpu_cfg)
 		.pingpong = sc7180_pp,
 		.intf_count = ARRAY_SIZE(sc7180_intf),
 		.intf = sc7180_intf,
+		.wb_count = ARRAY_SIZE(sm8250_wb),
+		.wb = sm8250_wb,
 		.vbif_count = ARRAY_SIZE(sdm845_vbif),
 		.vbif = sdm845_vbif,
 		.reg_dma_count = 1,