dmaengine: linux/dmaengine.h: drop duplicated word in a comment

Drop the doubled word "has" in a comment.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Vinod Koul <vkoul@kernel.org>
Cc: dmaengine@vger.kernel.org
Link: https://lore.kernel.org/r/06e64046-ebf1-15db-dbaf-73698de3b493@infradead.org


Signed-off-by: Vinod Koul <vkoul@kernel.org>