gpu: nvgpu: vgpu: set ch timeout value to 5s

It couldn't be zero, since it won't enable wdt.

JIRA VFND-3450

Change-Id: I9f6ab37bd438923596406a085603c70dcb83d46a
Signed-off-by: Richard Zhao <rizhao@nvidia.com>
Reviewed-on: http://git-master/r/1292715
Reviewed-by: Thomas Fleury <tfleury@nvidia.com>
Reviewed-by: svccoveritychecker <svccoveritychecker@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Alex Waterman <alexw@nvidia.com>
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

drivers/gpu/nvgpu/gk20a/platform_vgpu_tegra.c

@@ -60,6 +60,8 @@ struct gk20a_platform vgpu_tegra_platform = {
 	.enable_elpg            = false,
 	.enable_aelpg           = false,
 
+	.ch_wdt_timeout_ms = 5000,
+
 	.probe = gk20a_tegra_probe,
 	.default_big_page_size	= SZ_128K,