The $ref for "intel,dma-poll-cnt" is missing an '/', causing
dt_binding_check to fail. Fix this.

Fixes: afd4df85 ("dt-bindings: dma: Add bindings for Intel LGM SoC")
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210120180939.1580984-1-bjorn.andersson@linaro.orgSigned-off-by: Vinod Koul <vkoul@kernel.org>