dmaengine: mmp_pdma: Demote obvious misuse of kerneldoc to standard comment blocks

No attempt has been made to document any of the demoted functions here.

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

 drivers/dma/mmp_pdma.c:298: warning: Function parameter or member 'chan' not described in 'start_pending_queue'
 drivers/dma/mmp_pdma.c:393: warning: Function parameter or member 'dchan' not described in 'mmp_pdma_alloc_chan_resources'
 drivers/dma/mmp_pdma.c:862: warning: Function parameter or member 'dchan' not described in 'mmp_pdma_issue_pending'

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20200714111546.1755231-5-lee.jones@linaro.org


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