radeonsi: apply the double EVENT_WRITE_EOP workaround to VI as well

Internal docs don't mention it, but they also don't mention that the bug
has been fixed (like other CI bugs fixed in VI).

Vulkan does this too.

v2: also update r600_gfx_write_fence_dwords

Cc: 13.0 <mesa-stable@lists.freedesktop.org>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com> (v1)

src/gallium/drivers/radeon/r600_pipe_common.c

@@ -102,7 +102,8 @@ void r600_gfx_write_event_eop(struct r600_common_context *ctx,
 		      EVENT_INDEX(5) |
 		      event_flags;
 
-	if (ctx->chip_class == CIK) {
+	if (ctx->chip_class == CIK ||
+	    ctx->chip_class == VI) {
 		/* Two EOP events are required to make all engines go idle
 		 * (and optional cache flushes executed) before the timestamp
 		 * is written.
@@ -131,7 +132,8 @@ unsigned r600_gfx_write_fence_dwords(struct r600_common_screen *screen)
 {
 	unsigned dwords = 6;
 
-	if (screen->chip_class == CIK)
+	if (screen->chip_class == CIK ||
+	    screen->chip_class == VI)
 		dwords *= 2;
 
 	if (!screen->info.has_virtual_memory)