Revert "vm_tools: Allow vulkan in arcvm_dev.conf"

This reverts commit 9b7776315a2e8506c06675ecf2be964516b38317.

Reason for revert: looks like it breaks some tast.arc.* tests (b/188209009).

Original change's description:
> vm_tools: Allow vulkan in arcvm_dev.conf
>
> With this, a dev mode device with a vulkan enabled gpu driver will
> get vulkan enabled. Devices without vulkan enabled gpu driver still
> work fine.
>
> BUG=b:176196446
> TEST=manual - run ARCVM on hatch with this CL
>
> Change-Id: Ice301952bb4aa467e7593380a7939c1eb2d38421
> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/2892028
> Tested-by: Lepton Wu <lepton@chromium.org>
> Auto-Submit: Lepton Wu <lepton@chromium.org>
> Reviewed-by: Yiwei Zhang <zzyiwei@chromium.org>
> Reviewed-by: Chirantan Ekbote <chirantan@chromium.org>
> Commit-Queue: Lepton Wu <lepton@chromium.org>

Bug: b:176196446
Change-Id: I131cc7d5ef80580f844d35c4f6b2a6581b679e2d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/2898394
Reviewed-by: Andres Calderon Jaramillo <andrescj@google.com>
Auto-Submit: Andres Calderon Jaramillo <andrescj@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Andres Calderon Jaramillo <andrescj@chromium.org>
diff --git a/vm_tools/init/arcvm_dev.conf b/vm_tools/init/arcvm_dev.conf
index 260330e..9c3f9fe 100644
--- a/vm_tools/init/arcvm_dev.conf
+++ b/vm_tools/init/arcvm_dev.conf
@@ -60,8 +60,3 @@
 # Add serial-based earlycon and virtio-console logging.
 --serial=type=syslog,hardware=serial,num=1,earlycon=true
 --serial=type=syslog,hardware=virtio-console,num=1,console=true
-
-# Always enable vulkan. This is a no-op for most devices unless they carry a
-# vulkan enabled guest gpu driver.
-# TODO: remove this when we launch vulkan for ARCVM and move this to C++ code.
---gpu=vulkan=true