gpu: nvgpu: add polling for back-to-back error reporting in av+l

When an error is reported to Safety_Services, it will be cleared
at FSI and reported to SEH (System Error Handler). Since MISC_EC
interface provides only one register for error reporting, there
is a need to poll the status of previously reported error before
reporting the next error. For this purpose, this patch adds logic
to perform polling using epl_get_misc_ec_err_status(), in AV+L.

JIRA NVGPU-8094
Bug 200729736

Change-Id: Ia01a2fc42a7ce586b7965a82c90027a9a2dd252b
Signed-off-by: Rajesh Devaraj <rdevaraj@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2684141
Reviewed-by: Dinesh T <dt@nvidia.com>
Reviewed-by: Ankur Kishore <ankkishore@nvidia.com>
GVS: Gerrit_Virtual_Submit

drivers/gpu/nvgpu/os/linux/module.c

@@ -452,6 +452,10 @@ int gk20a_pm_finalize_poweron(struct device *dev)
 		}
 	}
 
+#ifdef CONFIG_NVGPU_ENABLE_MISC_EC
+	g->enable_polling = false;
+#endif
+
 	err = gk20a_restore_registers(g);
 	if (err)
 		goto done;