dma: dw: fix include for chan_data

The conditional definitions are not correct as "chan_data"
is used without any include guards, but defined only if
CONFIG_DMA_DW_HW_LLI or CONFIG_DMA_DW_SUSPEND_DRAIN is defined.
Correct the declaration to match usage.

Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>