gpu: nvgpu: gm20b: Enable rail-gating with max delay

Enable gpu rail gating with INT_MAX delay. This will allow
teams to experiment with different rail-gate entry delay.

Change-Id: I8c696140aba2374c797365282999b6589432047c
Signed-off-by: Seshendra Gadagottu <sgadagottu@nvidia.com>
Reviewed-on: http://git-master/r/491615
GVS: Gerrit_Virtual_Submit
Reviewed-by: Mitch Luban <mluban@nvidia.com>

drivers/gpu/nvgpu/gk20a/platform_gk20a_tegra.c

@@ -569,10 +569,10 @@ struct gk20a_platform gm20b_tegra_platform = {
 	.has_syncpoints = true,
 
 	/* power management configuration */
-	.railgate_delay		= 500,
+	.railgate_delay		= INT_MAX,
 	.clockgate_delay	= 50,
 	/* Disable all power features for gm20b */
-	.can_railgate           = false,
+	.can_railgate           = true,
 	.enable_slcg            = false,
 	.enable_blcg            = false,
 	.enable_elcg            = false,