dma: mmp_pdma: add IRQF_SHARED when request irq

For some SOCes use mmp_pdma, they have several dma controllers
sharing same irq.
So add IRQF_SHARED to flag when request irq. It can make multiple
controllers share the same irq.

Signed-off-by: Chao Xie <chao.xie@marvell.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>