dmaengine: edma: DT: Change reserved slot array from 16bit to 32bit type

This change makes the DT file to be easier to read since the reserved slots
array does not need the '/bits/ 16' to be specified, which might confuse
some people.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>