drm_hwcomposer: fix check for valid fence fd for in fences

The check for a valid fence fd is inverted, so we're failing to pass
IN_FENCE_FD's to the kernel when we have a valid fence.

Reported-by: Alexandru-Cosmin Gheorghe <Alexandru-Cosmin.Gheorghe@arm.com>
Reviewed-by: Robert Foss <robert.foss@collabora.com>
Signed-off-by: Rob Herring <robh@kernel.org>
1 file changed