dmaengine: mediatek: mtk-hsdma: Fix formatting in 'struct mtk_hsdma_pdesc' doc block

dmaengine: mediatek: mtk-hsdma: Fix formatting in 'struct mtk_hsdma_pdesc' doc block

Struct attribute names must be an exact match or the kerneldoc checker
gets confused.

Fixes the following W=1 kernel build warning(s):

 drivers/dma/mediatek/mtk-hsdma.c:120: warning: Function parameter or member 'desc1' not described in 'mtk_hsdma_pdesc'
 drivers/dma/mediatek/mtk-hsdma.c:120: warning: Function parameter or member 'desc2' not described in 'mtk_hsdma_pdesc'
 drivers/dma/mediatek/mtk-hsdma.c:120: warning: Function parameter or member 'desc3' not described in 'mtk_hsdma_pdesc'
 drivers/dma/mediatek/mtk-hsdma.c:120: warning: Function parameter or member 'desc4' not described in 'mtk_hsdma_pdesc'

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Cc: Sean Wang <sean.wang@mediatek.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: linux-mediatek@lists.infradead.org
Link: https://lore.kernel.org/r/20200714111546.1755231-2-lee.jones@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>