drm/vc4: Correct logging string for dev_err_probe

The commit that changed from dev_err to dev_err_probe left the %d in the
format string, but removed the parameter, leading to a compile
warning.

Fixes: "6505412d drm/vc4: Use dev_err_probe when logging error registering HDMI audio"
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>