drm/msm: Add a way to override processes comm/cmdline

In the cause of using the GPU via virtgpu, the host side process is
really a sort of proxy, and not terribly interesting from the PoV of
crash/fault logging.  Add a way to override these per process so that
we can see the guest process's name.

v2: Handle kmalloc failure, add comment to explain kstrdup returns
    NULL if passed NULL [Dan Carpenter]

Signed-off-by: Rob Clark <robdclark@chromium.org>
Link: https://lore.kernel.org/r/20220317165144.222101-4-robdclark@gmail.com
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/msm_submitqueue.c

@@ -61,6 +61,8 @@ void __msm_file_private_destroy(struct kref *kref)
 	}
 
 	msm_gem_address_space_put(ctx->aspace);
+	kfree(ctx->comm);
+	kfree(ctx->cmdline);
 	kfree(ctx);
 }